Multiconfigurational methods#

Strong/static correlation#

As we can see from perturbation theory, the largest contributions to the correlation energy typically comes from small denominators, that is from excitations from and to orbitals around the Fermi level. This suggest using a multi-scame approach to correlation, with an accurate method to describe correlation coming from a few orbitals located near the Fermi level and a cheaper but less accurate method for the rest.

In particular, in some situations, a few orbitals can have such large correlation effects that most electronic structure methods fail, sometimes dramatically. In those situations, the Hartree-Fock reference, upon which most other electronic structure methods are based, is not even qualitatively correct. One of the few methods able to describe such systems is configuration interaction, which then shows several determinants with significant weights.

One simple example of this is what happens during homolytic bond dissociation.

import veloxchem as vlx
import multipsi as mtp
import numpy as np
import matplotlib.pyplot as plt
import scipy.linalg
* Warning * Environment variable OMP_NUM_THREADS not set.
* Warning * Setting OMP_NUM_THREADS to 8.
* Warning * Setting MKL_THREADING_LAYER to "GNU".
# HF and CI calculation of OH.

mol_str="""
O 0.0000 0.0000  0.0000
H 0.0000 0.8957 -0.3167
"""

molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
molecule.set_multiplicity(2)
basis = vlx.MolecularBasis.read(molecule,"STO-3G")
scfdrv = vlx.ScfUnrestrictedDriver()
scfdrv.compute(molecule, basis)
E_OH_hf = scfdrv.get_scf_energy()

space = mtp.OrbSpace(molecule,scfdrv.mol_orbs)
space.FCI()
CIdrv = mtp.CIDriver()
CIdrv.compute(molecule, basis, space)
E_OH_FCI = CIdrv.getEnergy(0)


# HF calculation of H, equivalent to CI
mol_str = "H 0.0000 0.0000 0.0000"
molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
molecule.set_multiplicity(2)
basis = vlx.MolecularBasis.read(molecule,"STO-3G")
scfdrv.compute(molecule, basis)
E_H_hf = scfdrv.get_scf_energy()

#HF and CI calculations of water with stretching of one O-H bond

mol_template = """
O 0.0000 0.0000  0.0000
H 0.0000 0.8957 -0.3167
H 0.0000 0.0000  OHdist
"""
scfdrv = vlx.ScfRestrictedDriver()
distlist = [0.7,0.8,0.9,0.95,1.1,1.3,1.5,1.7,2,2.5,3,4,5]
E_hf = []
E_FCI = []
NON = []

#scf_settings = {'checkpoint_file': 'H2O.scf.h5','restart': 'yes'} #We reuse the previously converged orbitals at each step
#scfdrv.update_settings(scf_settings, {})

#Scan over O-H distances
for dist in distlist:
    mol_str = mol_template.replace("OHdist", str(dist))
    molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
    basis = vlx.MolecularBasis.read(molecule,"STO-3G")
    scfdrv.compute(molecule, basis)
    E_hf.append(scfdrv.get_scf_energy()-E_H_hf-E_OH_hf)
    
    space=mtp.OrbSpace(molecule,scfdrv.mol_orbs)
    space.FCI()
    CIdrv.compute(molecule,basis,space)
    E_FCI.append(CIdrv.getEnergy(0)-E_H_hf-E_OH_FCI)
    NON.append(CIdrv.getNON(0)) #Get the natural occupation numbers
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Unrestricted Hartree-Fock                                       
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 4.4560381191 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.02 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.360012981856 a.u. Time: 0.04 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.360013146479    0.0000000000      0.00041450      0.00010829      0.00000000                
                  2       -74.360013243297   -0.0000000968      0.00014187      0.00004657      0.00070172                
                  3       -74.360013252083   -0.0000000088      0.00001350      0.00000561      0.00019968                
                  4       -74.360013252125   -0.0000000000      0.00000027      0.00000007      0.00001041                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Unrestricted Hartree-Fock:                                                                            
               -------------------------------                                                                            
               Total Energy                       :      -74.3600132521 a.u.                                              
               Electronic Energy                  :      -78.8160513712 a.u.                                              
               Nuclear Repulsion Energy           :        4.4560381191 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002660 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Magnetic Quantum Number (M_S) :  0.5                                                                       
               Expectation value of S**2     :  0.7529                                                                    
                                                                                                                          
                                                                                                                          
                                             Spin Unrestricted Alpha Orbitals                                             
                                             --------------------------------                                             
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:  -20.28465 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -1.29831 a.u.                                                                  
               (   1 O   1s  :    -0.25) (   1 O   2s  :     0.92) (   2 H   1s  :     0.17)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.55554 a.u.                                                                  
               (   1 O   2s  :     0.47) (   1 O   1p-1:    -0.66) (   1 O   1p0 :     0.23)                              
               (   2 H   1s  :    -0.49)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.52523 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.43034 a.u.                                                                  
               (   1 O   1p-1:     0.33) (   1 O   1p0 :     0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.64072 a.u.                                                                  
               (   1 O   2s  :    -0.63) (   1 O   1p-1:    -0.82) (   1 O   1p0 :     0.29)                              
               (   2 H   1s  :     1.17)                                                                                  
                                                                                                                          
                                             Spin Unrestricted Beta Orbitals                                              
                                             -------------------------------                                              
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:  -20.25622 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -1.13565 a.u.                                                                  
               (   1 O   1s  :    -0.23) (   1 O   2s  :     0.86) (   2 H   1s  :     0.25)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.50671 a.u.                                                                  
               (   1 O   2s  :    -0.55) (   1 O   1p-1:     0.63) (   1 O   1p0 :    -0.22)                              
               (   2 H   1s  :     0.52)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.37857 a.u.                                                                  
               (   1 O   1p-1:    -0.33) (   1 O   1p0 :    -0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.35925 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67666 a.u.                                                                  
               (   1 O   2s  :    -0.65) (   1 O   1p-1:    -0.84) (   1 O   1p0 :     0.30)                              
               (   2 H   1s  :     1.14)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              6
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(9,6)

          CI expansion:
          -------------
Number of determinants:      90


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.383296229     0.0e+00      9.4e-29   0:00:00
                                                                                                                          
** Convergence reached in 1 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.38329622937891
- S^2   : 0.75  (multiplicity = 2.0 )
- Natural orbitals
2.00000 1.99932 1.99869 1.97455 1.00000 0.02745
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Unrestricted Hartree-Fock                                       
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 0.0000000000 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -0.466581850378 a.u. Time: 0.01 sec.                                   
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1        -0.466581850378    0.0000000000      0.00000000      0.00000000      0.00000000                
                                                                                                                          
               *** SCF converged in 1 iterations. Time: 0.00 sec.                                                         
                                                                                                                          
               Spin-Unrestricted Hartree-Fock:                                                                            
               -------------------------------                                                                            
               Total Energy                       :       -0.4665818504 a.u.                                              
               Electronic Energy                  :       -0.4665818504 a.u.                                              
               Nuclear Repulsion Energy           :        0.0000000000 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000000000 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Magnetic Quantum Number (M_S) :  0.5                                                                       
               Expectation value of S**2     :  0.7500                                                                    
                                                                                                                          
                                                                                                                          
                                             Spin Unrestricted Alpha Orbitals                                             
                                             --------------------------------                                             
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.46658 a.u.                                                                  
               (   1 H   1s  :     1.00)                                                                                  
                                                                                                                          
                                             Spin Unrestricted Beta Orbitals                                              
                                             -------------------------------                                              
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.30802 a.u.                                                                  
               (   1 H   1s  :     1.00)                                                                                  
                                                                                                                          
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 10.8943215511 a.u.                                                                     
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.784232379690 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.784232381291    0.0000000000      0.00002641      0.00000564      0.00000000                
                  2       -74.784232381522   -0.0000000002      0.00000496      0.00000110      0.00002485                
                  3       -74.784232381530   -0.0000000000      0.00000056      0.00000012      0.00000587                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.7842323815 a.u.                                              
               Electronic Energy                  :      -85.6785539326 a.u.                                              
               Nuclear Repulsion Energy           :       10.8943215511 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000005602 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23746 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.36475 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.78) (   1 O   1p0 :    -0.18)                              
               (   3 H   1s  :    -0.20)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.69722 a.u.                                                                  
               (   1 O   2s  :    -0.18) (   1 O   1p-1:    -0.31) (   1 O   1p0 :     0.54)                              
               (   2 H   1s  :    -0.45) (   3 H   1s  :     0.38)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.46163 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.69) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.26) (   3 H   1s  :     0.16)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40947 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65151 a.u.                                                                  
               (   1 O   2s  :     0.90) (   1 O   1p-1:     0.77) (   2 H   1s  :    -1.12)                              
               (   3 H   1s  :    -0.38)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    1.03794 a.u.                                                                  
               (   1 O   2s  :     0.91) (   1 O   1p-1:    -0.24) (   1 O   1p0 :     1.06)                              
               (   2 H   1s  :     0.37) (   3 H   1s  :    -1.57)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.819792717     0.0e+00      1.7e-03   0:00:00
        2     -74.819831082    -3.8e-05      8.4e-07   0:00:00
        3     -74.819831113    -3.1e-08      3.4e-10   0:00:00
        4     -74.819831113    -1.1e-11      2.0e-13   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.81983111274438
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99854 1.99840 1.99225 1.97839 0.02329 0.00913
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 10.1174669778 a.u.                                                                     
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.902863986779 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.902863988131    0.0000000000      0.00002196      0.00000452      0.00000000                
                  2       -74.902863988287   -0.0000000002      0.00000594      0.00000121      0.00001903                
                  3       -74.902863988299   -0.0000000000      0.00000041      0.00000009      0.00000728                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9028639883 a.u.                                              
               Electronic Energy                  :      -85.0203309661 a.u.                                              
               Nuclear Repulsion Energy           :       10.1174669778 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000004138 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.22958 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.31625 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.80) (   3 H   1s  :    -0.19)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.67053 a.u.                                                                  
               (   1 O   1p-1:    -0.32) (   1 O   1p0 :     0.52) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.42)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.45180 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.68) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.20)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39720 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.64675 a.u.                                                                  
               (   1 O   2s  :     0.92) (   1 O   1p-1:     0.75) (   2 H   1s  :    -1.07)                              
               (   3 H   1s  :    -0.49)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.90591 a.u.                                                                  
               (   1 O   2s  :     0.58) (   1 O   1p-1:    -0.32) (   1 O   1p0 :     0.99)                              
               (   2 H   1s  :     0.48) (   3 H   1s  :    -1.30)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)
          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.942614914     0.0e+00      1.5e-03   0:00:00
        2     -74.942648616    -3.4e-05      7.3e-07   0:00:00
        3     -74.942648644    -2.7e-08      3.0e-10   0:00:00
        4     -74.942648644    -9.5e-12      1.8e-13   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.94264864351192
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99842 1.99823 1.98805 1.97760 0.02406 0.01364
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 9.5100891999 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.951107391799 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.951107393386    0.0000000000      0.00002210      0.00000475      0.00000000                
                  2       -74.951107393536   -0.0000000001      0.00000746      0.00000151      0.00001842                
                  3       -74.951107393557   -0.0000000000      0.00000035      0.00000007      0.00001006                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9511073936 a.u.                                              
               Electronic Energy                  :      -84.4611965934 a.u.                                              
               Nuclear Repulsion Energy           :        9.5100891999 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003482 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23097 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.27988 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.82) (   2 H   1s  :    -0.15)                              
               (   3 H   1s  :    -0.17)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.64311 a.u.                                                                  
               (   1 O   1p-1:     0.33) (   1 O   1p0 :    -0.50) (   2 H   1s  :     0.44)                              
               (   3 H   1s  :    -0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44479 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.66) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38991 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.62457 a.u.                                                                  
               (   1 O   2s  :    -0.94) (   1 O   1p-1:    -0.67) (   1 O   1p0 :    -0.28)                              
               (   2 H   1s  :     0.93) (   3 H   1s  :     0.69)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.80222 a.u.                                                                  
               (   1 O   2s  :    -0.21) (   1 O   1p-1:     0.48) (   1 O   1p0 :    -0.90)                              
               (   2 H   1s  :    -0.70) (   3 H   1s  :     1.02)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)
          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.995946119     0.0e+00      1.3e-03   0:00:00
        2     -74.995975428    -2.9e-05      6.4e-07   0:00:00
        3     -74.995975451    -2.4e-08      2.7e-10   0:00:00
        4     -74.995975451    -8.3e-12      1.7e-13   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.99597545132619
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99832 1.99806 1.98169 1.97668 0.02480 0.02045
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 9.2533662788 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.959294729176 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.959294731276    0.0000000000      0.00002652      0.00000641      0.00000000                
                  2       -74.959294731494   -0.0000000002      0.00000888      0.00000203      0.00002222                
                  3       -74.959294731525   -0.0000000000      0.00000049      0.00000011      0.00001223                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9592947315 a.u.                                              
               Electronic Energy                  :      -84.2126610104 a.u.                                              
               Nuclear Repulsion Energy           :        9.2533662788 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000004855 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23339 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.26583 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.83) (   2 H   1s  :    -0.16)                              
               (   3 H   1s  :    -0.16)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.62936 a.u.                                                                  
               (   1 O   1p-1:    -0.35) (   1 O   1p0 :     0.49) (   2 H   1s  :    -0.44)                              
               (   3 H   1s  :     0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44172 a.u.                                                                  
               (   1 O   2s  :    -0.52) (   1 O   1p-1:     0.65) (   1 O   1p0 :     0.46)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.27)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38767 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.60306 a.u.                                                                  
               (   1 O   2s  :    -0.91) (   1 O   1p-1:    -0.58) (   1 O   1p0 :    -0.41)                              
               (   2 H   1s  :     0.81) (   3 H   1s  :     0.81)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.76612 a.u.                                                                  
               (   1 O   1p-1:    -0.58) (   1 O   1p0 :     0.82) (   2 H   1s  :     0.84)                              
               (   3 H   1s  :    -0.84)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -75.007093354     0.0e+00      1.2e-03   0:00:00
        2     -75.007120740    -2.7e-05      6.0e-07   0:00:00
        3     -75.007120762    -2.2e-08      2.5e-10   0:00:00
        4     -75.007120762    -7.8e-12      1.6e-13   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -75.00712076245553
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99828 1.99798 1.97810 1.97542 0.02562 0.02459
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 8.6203186612 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.947250973879 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.947250981138    0.0000000000      0.00006046      0.00001095      0.00000000                
                  2       -74.947250982569   -0.0000000014      0.00001394      0.00000251      0.00006130                
                  3       -74.947250982654   -0.0000000001      0.00000159      0.00000036      0.00001805                
                  4       -74.947250982655   -0.0000000000      0.00000011      0.00000002      0.00000116                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9472509827 a.u.                                              
               Electronic Energy                  :      -83.5675696438 a.u.                                              
               Nuclear Repulsion Energy           :        8.6203186612 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000001106 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.24331 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.23684 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.85) (   2 H   1s  :    -0.18)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.59041 a.u.                                                                  
               (   1 O   1p-1:    -0.41) (   1 O   1p0 :     0.44) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.43)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.43151 a.u.                                                                  
               (   1 O   2s  :    -0.49) (   1 O   1p-1:     0.60) (   1 O   1p0 :     0.49)                              
               (   2 H   1s  :     0.24) (   3 H   1s  :     0.35)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38490 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.50463 a.u.                                                                  
               (   1 O   2s  :    -0.69) (   1 O   1p-1:    -0.34) (   1 O   1p0 :    -0.66)                              
               (   2 H   1s  :     0.44) (   3 H   1s  :     0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.71372 a.u.                                                                  
               (   1 O   2s  :     0.41) (   1 O   1p-1:     0.76) (   1 O   1p0 :    -0.58)                              
               (   2 H   1s  :    -1.08) (   3 H   1s  :     0.41)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)
          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -75.005979386     0.0e+00      9.9e-04   0:00:00
        2     -75.006002050    -2.3e-05      4.8e-07   0:00:00
        3     -75.006002068    -1.8e-08      1.9e-10   0:00:00
        4     -75.006002068    -6.1e-12      1.3e-13   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -75.00600206764959
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99819 1.99780 1.97589 1.95606 0.04613 0.02594
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.9988271207 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.890314714542 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.890314747186    0.0000000000      0.00014197      0.00002435      0.00000000                
                  2       -74.890314758258   -0.0000000111      0.00001785      0.00000501      0.00020530                
                  3       -74.890314758311   -0.0000000001      0.00000391      0.00000087      0.00000745                
                  4       -74.890314758316   -0.0000000000      0.00000027      0.00000006      0.00000328                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.8903147583 a.u.                                              
               Electronic Energy                  :      -82.8891418791 a.u.                                              
               Nuclear Repulsion Energy           :        7.9988271207 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002694 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.25675 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21900 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.87) (   2 H   1s  :     0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.55250 a.u.                                                                  
               (   1 O   2s  :    -0.30) (   1 O   1p-1:     0.52) (   1 O   1p0 :    -0.34)                              
               (   2 H   1s  :     0.48) (   3 H   1s  :    -0.36)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40888 a.u.                                                                  
               (   1 O   2s  :     0.40) (   1 O   1p-1:    -0.50) (   1 O   1p0 :    -0.56)                              
               (   2 H   1s  :    -0.17) (   3 H   1s  :    -0.48)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38682 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.37290 a.u.                                                                  
               (   1 O   2s  :    -0.47) (   1 O   1p-1:    -0.22) (   1 O   1p0 :    -0.71)                              
               (   2 H   1s  :     0.24) (   3 H   1s  :     0.88)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.69116 a.u.                                                                  
               (   1 O   2s  :    -0.56) (   1 O   1p-1:    -0.81) (   1 O   1p0 :     0.43)                              
               (   2 H   1s  :     1.14) (   3 H   1s  :    -0.21)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.969486839     0.0e+00      8.0e-04   0:00:00
        2     -74.969505186    -1.8e-05      3.7e-07   0:00:00
        3     -74.969505200    -1.4e-08      1.4e-10   0:00:00
        4     -74.969505200    -4.6e-12      6.7e-14   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.96950520004206
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99823 1.99772 1.97487 1.90309 0.09924 0.02685
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.5395732848 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.820748583254 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.820748697856    0.0000000000      0.00026411      0.00004348      0.00000000                
                  2       -74.820748745254   -0.0000000474      0.00008006      0.00002170      0.00039160                
                  3       -74.820748747305   -0.0000000021      0.00000755      0.00000219      0.00006846                
                  4       -74.820748747316   -0.0000000000      0.00000035      0.00000008      0.00000419                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.8207487473 a.u.                                              
               Electronic Energy                  :      -82.3603220321 a.u.                                              
               Nuclear Repulsion Energy           :        7.5395732848 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003470 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26675 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21338 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53488 a.u.                                                                  
               (   1 O   2s  :    -0.42) (   1 O   1p-1:     0.60) (   1 O   1p0 :    -0.25)                              
               (   2 H   1s  :     0.50) (   3 H   1s  :    -0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39126 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.37376 a.u.                                                                  
               (   1 O   2s  :    -0.28) (   1 O   1p-1:     0.38) (   1 O   1p0 :     0.61)                              
               (   3 H   1s  :     0.58)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.27265 a.u.                                                                  
               (   1 O   2s  :     0.33) (   1 O   1p-1:     0.19) (   1 O   1p0 :     0.71)                              
               (   2 H   1s  :    -0.16) (   3 H   1s  :    -0.82)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67914 a.u.                                                                  
               (   1 O   2s  :     0.60) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.37)                              
               (   2 H   1s  :    -1.15)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.928103784     0.0e+00      6.9e-04   0:00:00
        2     -74.928119616    -1.6e-05      2.9e-07   0:00:00
        3     -74.928119627    -1.1e-08      1.0e-10   0:00:00
        4     -74.928119627    -3.4e-12      5.1e-14   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.9281196271523
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99845 1.99785 1.97435 1.80815 0.19381 0.02739
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.1860927234 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.752738771110 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.752739005792    0.0000000000      0.00039094      0.00006232      0.00000000                
                  2       -74.752739106095   -0.0000001003      0.00026997      0.00005995      0.00057506                
                  3       -74.752739127892   -0.0000000218      0.00000716      0.00000145      0.00021464                
                  4       -74.752739127905   -0.0000000000      0.00000087      0.00000015      0.00000558                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.7527391279 a.u.                                              
               Electronic Energy                  :      -81.9388318513 a.u.                                              
               Nuclear Repulsion Energy           :        7.1860927234 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000008685 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27266 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21267 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52948 a.u.                                                                  
               (   1 O   2s  :    -0.47) (   1 O   1p-1:     0.64) (   1 O   1p0 :    -0.20)                              
               (   2 H   1s  :     0.50) (   3 H   1s  :    -0.17)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39571 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.33381 a.u.                                                                  
               (   1 O   2s  :     0.18) (   1 O   1p-1:    -0.31) (   1 O   1p0 :    -0.63)                              
               (   3 H   1s  :    -0.63)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.19876 a.u.                                                                  
               (   1 O   2s  :    -0.24) (   1 O   1p-1:    -0.19) (   1 O   1p0 :    -0.71)                              
               (   3 H   1s  :     0.78)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67104 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.34)                              
               (   2 H   1s  :    -1.15)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.895409655     0.0e+00      6.3e-04   0:00:00
        2     -74.895424047    -1.4e-05      2.2e-07   0:00:00
        3     -74.895424056    -9.5e-09      6.9e-11   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.8954240564562
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99874 1.99809 1.97422 1.67075 0.33060 0.02759
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.7857964358 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.665585583090 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.665585646980    0.0000000000      0.00020258      0.00003503      0.00000000                
                  2       -74.665585685136   -0.0000000382      0.00008519      0.00001498      0.00041646                
                  3       -74.665585686714   -0.0000000016      0.00002712      0.00000402      0.00003430                
                  4       -74.665585686970   -0.0000000003      0.00000166      0.00000040      0.00002448                
                  5       -74.665585686971   -0.0000000000      0.00000025      0.00000005      0.00000169                
                                                                                                                          
               *** SCF converged in 5 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.6655856870 a.u.                                              
               Electronic Energy                  :      -81.4513821228 a.u.                                              
               Nuclear Repulsion Energy           :        6.7857964358 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002543 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27543 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21368 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52865 a.u.                                                                  
               (   1 O   2s  :     0.50) (   1 O   1p-1:    -0.65) (   1 O   1p0 :     0.19)                              
               (   2 H   1s  :    -0.50)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40015 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.27895 a.u.                                                                  
               (   1 O   1p-1:     0.26) (   1 O   1p0 :     0.64) (   3 H   1s  :     0.67)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.12283 a.u.                                                                  
               (   1 O   1p-1:    -0.20) (   1 O   1p0 :    -0.70) (   3 H   1s  :     0.74)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66396 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.31)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.867057015     0.0e+00      5.9e-04   0:00:00
        2     -74.867070416    -1.3e-05      1.6e-07   0:00:00
        3     -74.867070424    -7.8e-09      3.3e-11   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.86707042368249
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99909 1.99843 1.97434 1.43906 0.56151 0.02757
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.3284422371 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.569858224801 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.569858132117    0.0000000000      0.00521476      0.00150205      0.00000000                
                  2       -74.569865336724   -0.0000072046      0.00024001      0.00005100      0.00324201                
                  3       -74.569865350065   -0.0000000133      0.00002776      0.00000510      0.00013608                
                  4       -74.569865350829   -0.0000000008      0.00000342      0.00000063      0.00006083                
                  5       -74.569865350835   -0.0000000000      0.00000037      0.00000007      0.00000470                
                                                                                                                          
               *** SCF converged in 5 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.5698653508 a.u.                                              
               Electronic Energy                  :      -80.8983075880 a.u.                                              
               Nuclear Repulsion Energy           :        6.3284422371 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003666 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27117 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21343 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52855 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.65) (   1 O   1p0 :    -0.20)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40147 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.21527 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.66) (   3 H   1s  :    -0.69)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.05301 a.u.                                                                  
               (   1 O   1p-1:     0.21) (   1 O   1p0 :     0.68) (   3 H   1s  :    -0.72)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66097 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.852560699     0.0e+00      5.7e-04   0:00:00
        2     -74.852573680    -1.3e-05      1.3e-07   0:00:00
        3     -74.852573687    -7.0e-09      6.5e-12   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.85257368663203
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99928 1.99865 1.97451 1.17266 0.82743 0.02747
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.0212086638 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.519848212310 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.519794238781    0.0000000000      0.01475594      0.00439714      0.00000000                
                  2       -74.519853099827   -0.0000588610      0.00035523      0.00008942      0.00920391                
                  3       -74.519853129182   -0.0000000294      0.00002293      0.00000453      0.00018756                
                  4       -74.519853129689   -0.0000000005      0.00001197      0.00000241      0.00004132                
                  5       -74.519853129784   -0.0000000001      0.00000224      0.00000038      0.00001878                
                  6       -74.519853129786   -0.0000000000      0.00000067      0.00000017      0.00000313                
                                                                                                                          
               *** SCF converged in 6 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.5198531298 a.u.                                              
               Electronic Energy                  :      -80.5410617936 a.u.                                              
               Nuclear Repulsion Energy           :        6.0212086638 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000006685 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26576 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21181 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52740 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.65) (   1 O   1p0 :     0.21)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40011 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.17962 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.67) (   3 H   1s  :    -0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.01834 a.u.                                                                  
               (   1 O   1p-1:     0.23) (   1 O   1p0 :     0.67) (   3 H   1s  :    -0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66180 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.850214334     0.0e+00      5.7e-04   0:00:00
        2     -74.850227256    -1.3e-05      1.3e-07   0:00:00
        3     -74.850227263    -6.9e-09      1.1e-12   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.85022726273016
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99931 1.99869 1.97454 1.05946 0.94055 0.02745
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 5.6344241715 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.084140230928 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.000503437704    0.0000000000      0.90532909      0.24131160      0.00000000                
                  2       -74.098394605837   -0.0978911681      0.59342893      0.16078738      0.18854771                
                  3       -74.127683290479   -0.0292886846      0.53156880      0.14521772      1.41709384                
                  4       -74.132164532108   -0.0044812416      0.51112112      0.13948385      0.01224419                
                  5       -74.132554495236   -0.0003899631      0.50908794      0.13886864      0.00122971                
                  6       -74.136771887308   -0.0042173921      0.48889199      0.13321685      0.01206759                
                  7       -74.120225737099    0.0165461502      0.49298083      0.13443188      1.41423531                
                  8       -74.102682049364    0.0175436877      0.63216124      0.17360742      1.41730265                
                  9       -74.044445006341    0.0582370430      0.78403569      0.21101672      1.43841747                
                 10       -73.490358679705    0.5540863266      1.55371286      0.40019647      1.57950486                
                 11       -73.954038182587   -0.4636795029      1.01876705      0.27054368      0.55911353                
                 12       -73.998169219382   -0.0441310368      0.91003156      0.24342941      1.41616308                
                 13       -73.974007936212    0.0241612832      0.97566371      0.25968020      1.41492158                
                 14       -74.090082746071   -0.1160748099      0.67628102      0.18615160      1.47238510                
                 15       -73.967426923666    0.1226558224      0.99037103      0.26345150      1.47513373                
                 16       -73.956402165260    0.0110247584      1.01368485      0.26913469      0.01851723                
                 17       -73.928217288737    0.0281848765      1.07026901      0.28349709      0.04339128                
                 18       -74.119717797807   -0.1915005091      0.56545876      0.15451358      1.47307697                
                 19       -74.116893183929    0.0028246139      0.57720387      0.15795048      0.00735957                
                 20       -74.149170302601   -0.0322771187      0.42355281      0.11489501      0.09178141                
                 21       -74.142417096029    0.0067532066      0.46034412      0.12512908      0.02187367                
                 22       -74.062608444707    0.0798086513      0.72620878      0.19569663      1.41987595                
                 23       -74.084035775979   -0.0214273313      0.65055232      0.17594707      0.04513318                
                 24       -74.126690934708   -0.0426551587      0.53577335      0.14632955      1.41982530                
                 25       -74.138932693280   -0.0122417586      0.47829996      0.13030564      0.03458099                
                 26       -73.981252426497    0.1576802668      0.95113652      0.25437538      1.44111351                
                 27       -74.000531905692   -0.0192794792      0.90495244      0.24270690      0.07778806                
                 28       -74.001429877267   -0.0008979716      0.90270289      0.24214257      0.08312853                
                 29       -74.128357521858   -0.1269276446      0.52833782      0.14424643      1.44059580                
                 30       -74.129766253930   -0.0014087321      0.52196657      0.14246093      0.00384756                
                 31       -74.133046175217   -0.0032799213      0.50679169      0.13821775      0.00934817                
                 32       -74.113095052664    0.0199511226      0.59247598      0.16228577      0.05168600                
                 33       -74.109650466301    0.0034445864      0.60580915      0.16602579      0.00825878                
                 34       -74.079882203175    0.0297682631      0.66604035      0.18004344      1.42530554                
                 35       -74.048444097465    0.0314381057      0.77138542      0.20744002      0.06655467                
                 36       -74.079157098690   -0.0307130012      0.71151389      0.19609186      1.44676276                
                 37       -74.069510285601    0.0096468131      0.74130212      0.20472102      0.01869294                
                 38       -74.075173297466   -0.0056630119      0.68340121      0.18482826      1.43984033                
                 39       -74.074528309716    0.0006449878      0.68565624      0.18542244      0.04077484                
                 40       -74.116429955902   -0.0419016462      0.57929420      0.15857323      1.42465273                
                 41       -74.034629080611    0.0818008753      0.81294973      0.21853829      1.43597199                
                 42       -74.023954691782    0.0106743888      0.86324252      0.24008746      1.47689395                
                 43       -74.104489522545   -0.0805348308      0.62539608      0.17156820      0.15324325                
                 44       -74.109752037844   -0.0052625153      0.54395474      0.14792029      1.41916753                
                 45       -74.113074388526   -0.0033223507      0.52876921      0.14386394      0.06065163                
                 46       -74.109077016277    0.0039973722      0.54706629      0.14875575      0.05020845                
                 47       -74.110122757689   -0.0010457414      0.54229444      0.14748056      0.01489100                
                 48       -74.069931476135    0.0401912816      0.74008231      0.20441043      1.42676037                
                 49       -74.107632801406   -0.0377013253      0.55358379      0.15047781      1.42762998                
                 50       -74.106751836029    0.0008809654      0.61742294      0.16925288      1.41921606                
                                                                                                                          
               *** SCF NOT converged in 50 iterations. Time: 0.14 sec.                                                    
                                                                                                                          
               *** Warning: SCF is not converged!                                                                         
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.849868097     0.0e+00      5.7e-04   0:00:00
        2     -74.849880967    -1.3e-05      1.2e-07   0:00:00
        3     -74.849880973    -6.3e-09      1.4e-14   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.84988097335345
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99931 1.99869 1.97455 1.00485 0.99515 0.02745
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 5.4008697288 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -73.928853308431 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -73.978581312823    0.0000000000      0.90210952      0.23928520      0.00000000                
                  2       -74.088914398175   -0.1103330854      0.53233794      0.14416166      0.22125263                
                  3       -74.071543936890    0.0173704613      0.64859470      0.17787135      1.41924556                
                  4       -74.092318322593   -0.0207743857      0.51630213      0.14023817      1.41846667                
                  5       -74.110390124780   -0.0180718022      0.48813516      0.13269078      1.41427159                
                  6       -74.093273540115    0.0171165847      0.51162178      0.13898654      1.41425009                
                  7       -74.093731177701   -0.0004576376      0.50936430      0.13838913      0.00128042                
                  8       -74.093975721119   -0.0002445434      0.50815336      0.13806842      0.00068614                
                  9       -74.094136567588   -0.0001608465      0.50735513      0.13785695      0.00045210                
                 10       -74.094254293227   -0.0001177256      0.50677004      0.13770192      0.00033131                
                 11       -74.093421694270    0.0008325990      0.51088482      0.13878503      0.00234652                
                 12       -74.078563638478    0.0148580558      0.62274342      0.17038064      1.41717662                
                 13       -74.093970701106   -0.0154070626      0.50816836      0.13806400      1.41707840                
                 14       -74.094192043185   -0.0002213421      0.50707439      0.13777726      0.00062870                
                 15       -74.094367841372   -0.0001757982      0.50620013      0.13754572      0.00049543                
                 16       -74.083141022338    0.0112268190      0.60585562      0.16577819      1.41635539                
                 17       -74.088834658232   -0.0056936359      0.58350229      0.15946681      0.01360101                
                 18       -74.110287244197   -0.0214525860      0.48866321      0.13285469      0.05691699                
                 19       -74.094468733304    0.0158185109      0.50570634      0.13741222      1.41423036                
                 20       -74.094549583546   -0.0000808502      0.50533846      0.13731134      0.00151776                
                 21       -74.094495141440    0.0000544421      0.50560679      0.13738273      0.00018291                
                 22       -74.094625059505   -0.0001299181      0.50496506      0.13721204      0.00041687                
                 23       -74.094653080006   -0.0000280205      0.50482948      0.13717696      0.00011133                
                 24       -74.094735697259   -0.0000826173      0.50442189      0.13706851      0.00027440                
                 25       -74.045588573907    0.0491471234      0.73371360      0.20229220      1.42276534                
                 26       -74.093095191283   -0.0475066174      0.51264404      0.13922052      1.42327000                
                 27       -74.075551896754    0.0175432945      0.59630964      0.16133444      0.05760453                
                 28       -74.093289432449   -0.0177375357      0.51155590      0.13896912      0.05560469                
                 29       -74.064590422157    0.0286990103      0.67268796      0.18476346      1.41945813                
                 30       -74.095703784756   -0.0311133626      0.55512306      0.15145798      0.07188763                
                 31       -74.103070531684   -0.0073667469      0.51683923      0.13465431      1.41106347                
                 32       -74.108275082925   -0.0052045512      0.50037716      0.13589795      1.40899330                
                 33       -74.167194296075   -0.0589192132      0.58175337      0.12199259      0.26928542                
                 34       -74.330771708616   -0.1635774125      0.57451596      0.12220221      0.34554502                
                 35       -74.454075397689   -0.1233036891      0.19150843      0.04287207      1.28920260                
                 36       -74.111544396006    0.3425310017      0.50598457      0.13506560      0.85186980                
                 37       -74.154567355952   -0.0430229599      0.57420568      0.12616666      0.32417489                
                 38       -74.264107977299   -0.1095406213      0.62346423      0.12511114      0.24756547                
                 39       -74.455479719600   -0.1913717423      0.17836840      0.03999310      0.47406932                
                 40       -74.142421355945    0.3130583637      0.55395386      0.12782704      1.06723349                
                 41       -74.319532445371   -0.1771110894      0.58636242      0.12390026      0.39306751                
                 42       -74.402799961951   -0.0832675166      0.43420591      0.09569757      0.18458956                
                 43       -74.436747684955   -0.0339477230      0.30502488      0.06792258      0.10303104                
                 44       -74.309393361628    0.1273543233      0.59591594      0.12500845      1.23476264                
                 45       -74.367578837606   -0.0581854760      0.51656388      0.11235599      1.13259870                
                 46       -74.371985594894   -0.0044067573      0.50898895      0.11076201      0.01041735                
                 47       -74.124932549943    0.2470530450      0.52331178      0.13093082      0.82017498                
                 48       -74.119006902428    0.0059256475      0.51295791      0.13223746      0.03131734                
                 49       -74.401982431236   -0.2829755288      0.43669454      0.09619578      0.85318593                
                 50       -74.112444136966    0.2895382943      0.49203484      0.13222833      0.80143973                
                                                                                                                          
               *** SCF NOT converged in 50 iterations. Time: 0.14 sec.                                                    
                                                                                                                          
               *** Warning: SCF is not converged!                                                                         
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              7
Number of virtual orbitals:             0

    This is a CASSCF wavefunction: CAS(10,7)

          CI expansion:
          -------------
Number of determinants:      231


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -74.849865165     0.0e+00      5.7e-04   0:00:00
        2     -74.849878078    -1.3e-05      1.4e-07   0:00:00
        3     -74.849878086    -7.2e-09      4.3e-12   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.84987808565761
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
2.00000 1.99932 1.99869 1.97455 1.00019 0.99981 0.02745
plt.figure(figsize=(6,4))
plt.title('Energy during O-H dissociation')
x = np.array(distlist)
y = np.array(E_FCI)
z = np.array(E_hf)
plt.plot(x,y, label='FullCI')
plt.plot(x,z, label='RHF')
plt.legend()
plt.tight_layout(); plt.show()
../../_images/mcscf_3_0.png

It is clear that while HF gives a reasonable energy around the equilibrium, it performs very poorly at longer O-H distances, failing to reach the sum of the energies of the two fragments OH\(^.\) and H\(^.\)). The SCF convergence is also very poor and can in some cases even fail.

The explanation can be found by looking at the occupation numbers of the CI, which shows that two orbitals are getting increasingly correlated. If we would plot them, we would see they correspond to the \(\sigma\) and \(\sigma^*\) orbitals.

plt.figure(figsize=(6,4))
plt.title('Natural occupation numbers during O-H dissociation')
x = np.array(distlist)
sigma=[]
sigma_star=[]
for NONi in NON:
    sigma.append(NONi[4]) #The natural orbitals are sorted by occupation numbers, so the most correlated are the "highest" of the HF occupied and the "lowest" of the HF empty
    sigma_star.append(NONi[5])
y = np.array(sigma)
z = np.array(sigma_star)
plt.plot(x, y, label='sigma')
plt.plot(x, z, label='sigma*')
plt.legend()
plt.tight_layout(); plt.show()
../../_images/mcscf_5_0.png

Clearly, at longer distances, the Hartree-Fock approximation of doubly occupied \(\sigma\) and empty \(\sigma^*\) becomes less and less reasonable.

On the other hand, even at long O-H distances, all occupation numbers remain reasonably close to the HF assumption, suggesting that we only needed to perform the CI over these two orbitals.

print("Natural orbital occupation numbers at 5Å")
print(NON[-1])
Natural orbital occupation numbers at 5Å
[1.9999994  1.99931502 1.9986904  1.97454512 1.00019271 0.99980729
 0.02745005]

Doing so would define an “active space” containing the two orbitals, while the other orbitals would be called “inactive”. Including all excitations within this active space, that performing a full CI within this small space, we define a so-called “complete active space” (CAS), and the method is thus called CASCI.

The Multiconfigurational Self-Consistent Field method (MCSCF)#

While the CASCI can be performed after a Hartree-Fock calculation, it has a major flaw in that the orbitals were optimized assuming the Hartree-Fock density was reasonable. But the main motivation behind CASCI was precisely that the Hartree-Fock density was wrong, and thus the Hartree-Fock orbitals are far from optimal. It is thus tempting to want to optimize the orbitals using the CASCI density. Of course, as the orbitals change, it is likely the CASCI would also need to be relaxed. Clearly, the process need to be self-consistent. The resulting method is called the multiconfigurational self-consistent field method (MCSCF), and if we used a complete active space, it can be called more specifically CASSCF.

MCSCF can be seen as a generalization of the self-consistent field concept of Hartree-Fock to a wavefunction containing several determinants. It simultaneously relaxes the orbitals and the CI coefficients.

Illustrative example#

Let us illustrate the MCSCF method by applying it to our O-H dissociation problem. As we mentioned, an active space containing the \(\sigma\) and \(\sigma^*\) is enough to qualitatively describe the bond-breaking. The simplest way to define this active space in the program is to mention the number of active orbitals (here 2) as well as the number of electrons in them (here also 2). We often use the notation CAS(\(m,n\)) with \(m\) the number of electrons and \(n\) the number of orbitals.

E_CASSCF=[]


Mcscfdrv=mtp.McscfDriver()
#Scan over O-H distances
for dist in distlist:
    mol_str = mol_template.replace("OHdist", str(dist))
    molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
    basis = vlx.MolecularBasis.read(molecule, "STO-3G")
    scfdrv.compute(molecule, basis)
    
    space = mtp.OrbSpace(molecule, scfdrv.mol_orbs)
    space.CAS(2,2)
    Mcscfdrv.compute(molecule, basis, space)
    E_CASSCF.append(Mcscfdrv.getEnergy(0)-E_H_hf-E_OH_hf)
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 10.8943215511 a.u.                                                                     
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.784232379690 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.784232381291    0.0000000000      0.00002641      0.00000564      0.00000000                
                  2       -74.784232381522   -0.0000000002      0.00000496      0.00000110      0.00002485                
                  3       -74.784232381530   -0.0000000000      0.00000056      0.00000012      0.00000587                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.7842323815 a.u.                                              
               Electronic Energy                  :      -85.6785539326 a.u.                                              
               Nuclear Repulsion Energy           :       10.8943215511 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000005602 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23746 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.36475 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.78) (   1 O   1p0 :    -0.18)                              
               (   3 H   1s  :    -0.20)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.69722 a.u.                                                                  
               (   1 O   2s  :    -0.18) (   1 O   1p-1:    -0.31) (   1 O   1p0 :     0.54)                              
               (   2 H   1s  :    -0.45) (   3 H   1s  :     0.38)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.46163 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.69) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.26) (   3 H   1s  :     0.16)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40947 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65151 a.u.                                                                  
               (   1 O   2s  :     0.90) (   1 O   1p-1:     0.77) (   2 H   1s  :    -1.12)                              
               (   3 H   1s  :    -0.38)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    1.03794 a.u.                                                                  
               (   1 O   2s  :     0.91) (   1 O   1p-1:    -0.24) (   1 O   1p0 :     1.06)                              
               (   2 H   1s  :     0.37) (   3 H   1s  :    -1.57)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.785213519     0.0e+00      3.8e-03          1   0:00:00
        2     -74.785370866    -1.6e-04      1.9e-03          1   0:00:00
        3     -74.785368899     2.0e-06      4.7e-03          1   0:00:00
        4     -74.785478129    -1.1e-04      1.2e-03          1   0:00:00
        5     -74.785488527    -1.0e-05      2.8e-04          1   0:00:00
        6     -74.785489682    -1.2e-06      4.1e-05          1   0:00:00
        7     -74.785489683    -1.2e-09      1.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 7 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.7854896827799
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99827 0.00173
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23887 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.36510 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.78) (   1 O   1p0 :    -0.18)                              
               (   3 H   1s  :    -0.20)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.69772 a.u.                                                                  
               (   1 O   2s  :     0.18) (   1 O   1p-1:     0.31) (   1 O   1p0 :    -0.54)                              
               (   2 H   1s  :     0.45) (   3 H   1s  :    -0.38)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.46230 a.u.                                                                  
               (   1 O   2s  :     0.53) (   1 O   1p-1:    -0.69) (   1 O   1p0 :    -0.45)                              
               (   2 H   1s  :    -0.26) (   3 H   1s  :    -0.16)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.998 Energy:   -0.40958 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.002 Energy:    0.72010 a.u.                                                                  
               (   1 O   2s  :    -1.20) (   1 O   1p-1:    -0.60) (   1 O   1p0 :    -0.40)                              
               (   2 H   1s  :     0.86) (   3 H   1s  :     1.01)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.96832 a.u.                                                                  
               (   1 O   2s  :     0.44) (   1 O   1p-1:    -0.54) (   1 O   1p0 :     0.98)                              
               (   2 H   1s  :     0.81) (   3 H   1s  :    -1.27)                                                        
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 10.1174669778 a.u.                                                                     
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.902863986779 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.902863988131    0.0000000000      0.00002196      0.00000452      0.00000000                
                  2       -74.902863988287   -0.0000000002      0.00000594      0.00000121      0.00001903                
                  3       -74.902863988299   -0.0000000000      0.00000041      0.00000009      0.00000728                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9028639883 a.u.                                              
               Electronic Energy                  :      -85.0203309661 a.u.                                              
               Nuclear Repulsion Energy           :       10.1174669778 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000004138 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.22958 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.31625 a.u.                                                                  
               (   1 O   1s  :    -0.23) (   1 O   2s  :     0.80) (   3 H   1s  :     0.19)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.67053 a.u.                                                                  
               (   1 O   1p-1:    -0.32) (   1 O   1p0 :     0.52) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.42)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.45180 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.68) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.20)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39720 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.64675 a.u.                                                                  
               (   1 O   2s  :     0.92) (   1 O   1p-1:     0.75) (   2 H   1s  :    -1.07)                              
               (   3 H   1s  :    -0.49)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.90591 a.u.                                                                  
               (   1 O   2s  :     0.58) (   1 O   1p-1:    -0.32) (   1 O   1p0 :     0.99)                              
               (   2 H   1s  :     0.48) (   3 H   1s  :    -1.30)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.903957198     0.0e+00      4.2e-03          1   0:00:00
        2     -74.904061755    -1.0e-04      1.7e-03          1   0:00:00
        3     -74.904113057    -5.1e-05      2.8e-03          1   0:00:00
        4     -74.904136325    -2.3e-05      2.8e-04          1   0:00:00
        5     -74.904136362    -3.7e-08      1.0e-04          1   0:00:00
        6     -74.904136365    -2.0e-09      2.0e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 6 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.90413636451567
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99811 0.00189
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23104 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.31660 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.80) (   3 H   1s  :    -0.19)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.67106 a.u.                                                                  
               (   1 O   1p-1:    -0.32) (   1 O   1p0 :     0.52) (   2 H   1s  :    -0.44)                              
               (   3 H   1s  :     0.42)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.45248 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.68) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.20)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.998 Energy:   -0.39729 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.002 Energy:    0.67628 a.u.                                                                  
               (   1 O   2s  :     1.06) (   1 O   1p-1:     0.59) (   1 O   1p0 :     0.40)                              
               (   2 H   1s  :    -0.84) (   3 H   1s  :    -0.90)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.87528 a.u.                                                                  
               (   1 O   2s  :     0.23) (   1 O   1p-1:    -0.56) (   1 O   1p0 :     0.91)                              
               (   2 H   1s  :     0.81) (   3 H   1s  :    -1.06)                                                        
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 9.5100891999 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.951107391798 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.951107393386    0.0000000000      0.00002210      0.00000475      0.00000000                
                  2       -74.951107393536   -0.0000000001      0.00000746      0.00000151      0.00001842                
                  3       -74.951107393557   -0.0000000000      0.00000035      0.00000007      0.00001006                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9511073936 a.u.                                              
               Electronic Energy                  :      -84.4611965934 a.u.                                              
               Nuclear Repulsion Energy           :        9.5100891999 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003482 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23097 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.27988 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.82) (   2 H   1s  :    -0.15)                              
               (   3 H   1s  :    -0.17)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.64311 a.u.                                                                  
               (   1 O   1p-1:     0.33) (   1 O   1p0 :    -0.50) (   2 H   1s  :     0.44)                              
               (   3 H   1s  :    -0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44479 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.66) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38991 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.62457 a.u.                                                                  
               (   1 O   2s  :    -0.94) (   1 O   1p-1:    -0.67) (   1 O   1p0 :    -0.28)                              
               (   2 H   1s  :     0.93) (   3 H   1s  :     0.69)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.80222 a.u.                                                                  
               (   1 O   2s  :     0.21) (   1 O   1p-1:    -0.48) (   1 O   1p0 :     0.90)                              
               (   2 H   1s  :     0.70) (   3 H   1s  :    -1.02)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.952348949     0.0e+00      4.6e-03          1   0:00:00
        2     -74.952373397    -2.4e-05      1.4e-03          1   0:00:00
        3     -74.952385956    -1.3e-05      1.3e-03          1   0:00:00
        4     -74.952386328    -3.7e-07      4.7e-04          1   0:00:00
        5     -74.952386382    -5.4e-08      2.5e-05          1   0:00:00
        6     -74.952386382    -1.4e-10      8.6e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 6 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.95238638226556
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99794 0.00206
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23249 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.28025 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.82) (   2 H   1s  :    -0.15)                              
               (   3 H   1s  :    -0.17)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.64366 a.u.                                                                  
               (   1 O   1p-1:    -0.33) (   1 O   1p0 :     0.50) (   2 H   1s  :    -0.44)                              
               (   3 H   1s  :     0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44548 a.u.                                                                  
               (   1 O   2s  :    -0.53) (   1 O   1p-1:     0.66) (   1 O   1p0 :     0.45)                              
               (   2 H   1s  :     0.27) (   3 H   1s  :     0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.998 Energy:   -0.38998 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.002 Energy:    0.62763 a.u.                                                                  
               (   1 O   2s  :    -0.96) (   1 O   1p-1:    -0.59) (   1 O   1p0 :    -0.41)                              
               (   2 H   1s  :     0.82) (   3 H   1s  :     0.83)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.79799 a.u.                                                                  
               (   1 O   1p-1:    -0.57) (   1 O   1p0 :     0.85) (   2 H   1s  :     0.83)                              
               (   3 H   1s  :    -0.91)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 9.2533662788 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.959294729176 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.959294731276    0.0000000000      0.00002652      0.00000641      0.00000000                
                  2       -74.959294731494   -0.0000000002      0.00000888      0.00000203      0.00002222                
                  3       -74.959294731525   -0.0000000000      0.00000049      0.00000011      0.00001223                
                                                                                                                          
               *** SCF converged in 3 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9592947315 a.u.                                              
               Electronic Energy                  :      -84.2126610104 a.u.                                              
               Nuclear Repulsion Energy           :        9.2533662788 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000004855 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23339 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.26583 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.83) (   2 H   1s  :    -0.16)                              
               (   3 H   1s  :    -0.16)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.62936 a.u.                                                                  
               (   1 O   1p-1:    -0.35) (   1 O   1p0 :     0.49) (   2 H   1s  :    -0.44)                              
               (   3 H   1s  :     0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44172 a.u.                                                                  
               (   1 O   2s  :     0.52) (   1 O   1p-1:    -0.65) (   1 O   1p0 :    -0.46)                              
               (   2 H   1s  :    -0.27) (   3 H   1s  :    -0.27)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38767 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.60306 a.u.                                                                  
               (   1 O   2s  :    -0.91) (   1 O   1p-1:    -0.58) (   1 O   1p0 :    -0.41)                              
               (   2 H   1s  :     0.81) (   3 H   1s  :     0.81)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.76612 a.u.                                                                  
               (   1 O   1p-1:     0.58) (   1 O   1p0 :    -0.82) (   2 H   1s  :    -0.84)                              
               (   3 H   1s  :     0.84)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.960569292     0.0e+00      4.5e-03          1   0:00:00
        2     -74.960574440    -5.1e-06      1.2e-03          1   0:00:00
        3     -74.960574754    -3.1e-07      7.9e-05          1   0:00:00
        4     -74.960574755    -1.2e-09      2.5e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.96057475512835
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99785 0.00215
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23495 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.26621 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.83) (   2 H   1s  :    -0.16)                              
               (   3 H   1s  :    -0.16)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.62992 a.u.                                                                  
               (   1 O   1p-1:    -0.35) (   1 O   1p0 :     0.49) (   2 H   1s  :    -0.44)                              
               (   3 H   1s  :     0.44)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.44241 a.u.                                                                  
               (   1 O   2s  :     0.52) (   1 O   1p-1:    -0.65) (   1 O   1p0 :    -0.46)                              
               (   2 H   1s  :    -0.27) (   3 H   1s  :    -0.27)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.998 Energy:   -0.38774 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.002 Energy:    0.60235 a.u.                                                                  
               (   1 O   2s  :    -0.91) (   1 O   1p-1:    -0.58) (   1 O   1p0 :    -0.41)                              
               (   2 H   1s  :     0.81) (   3 H   1s  :     0.81)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.76562 a.u.                                                                  
               (   1 O   1p-1:     0.58) (   1 O   1p0 :    -0.82) (   2 H   1s  :    -0.84)                              
               (   3 H   1s  :     0.84)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 8.6203186612 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.947250973879 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.947250981138    0.0000000000      0.00006046      0.00001095      0.00000000                
                  2       -74.947250982569   -0.0000000014      0.00001394      0.00000251      0.00006130                
                  3       -74.947250982654   -0.0000000001      0.00000159      0.00000036      0.00001805                
                  4       -74.947250982655   -0.0000000000      0.00000011      0.00000002      0.00000116                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9472509827 a.u.                                              
               Electronic Energy                  :      -83.5675696438 a.u.                                              
               Nuclear Repulsion Energy           :        8.6203186612 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000001106 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.24331 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.23684 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.85) (   2 H   1s  :    -0.18)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.59041 a.u.                                                                  
               (   1 O   1p-1:    -0.41) (   1 O   1p0 :     0.44) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.43)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.43151 a.u.                                                                  
               (   1 O   2s  :    -0.49) (   1 O   1p-1:     0.60) (   1 O   1p0 :     0.49)                              
               (   2 H   1s  :     0.24) (   3 H   1s  :     0.35)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38490 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.50463 a.u.                                                                  
               (   1 O   2s  :    -0.69) (   1 O   1p-1:    -0.34) (   1 O   1p0 :    -0.66)                              
               (   2 H   1s  :     0.44) (   3 H   1s  :     0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.71372 a.u.                                                                  
               (   1 O   2s  :     0.41) (   1 O   1p-1:     0.76) (   1 O   1p0 :    -0.58)                              
               (   2 H   1s  :    -1.08) (   3 H   1s  :     0.41)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.948389137     0.0e+00      4.3e-03          1   0:00:00
        2     -74.948457122    -6.8e-05      1.7e-03          1   0:00:00
        3     -74.948506244    -4.9e-05      4.2e-03          1   0:00:00
        4     -74.948528009    -2.2e-05      6.3e-04          1   0:00:00
        5     -74.948528185    -1.8e-07      2.8e-04          1   0:00:00
        6     -74.948528203    -1.8e-08      3.6e-05          1   0:00:00
        7     -74.948528204    -4.4e-10      9.2e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 7 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.94852820355517
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99756 0.00244
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.24501 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.23731 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.85) (   2 H   1s  :    -0.18)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.59103 a.u.                                                                  
               (   1 O   1p-1:    -0.41) (   1 O   1p0 :     0.44) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.43)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.43222 a.u.                                                                  
               (   1 O   2s  :     0.49) (   1 O   1p-1:    -0.60) (   1 O   1p0 :    -0.49)                              
               (   2 H   1s  :    -0.24) (   3 H   1s  :    -0.35)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.998 Energy:   -0.38497 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.002 Energy:    0.52504 a.u.                                                                  
               (   1 O   2s  :     0.79) (   1 O   1p-1:     0.56) (   1 O   1p0 :     0.44)                              
               (   2 H   1s  :    -0.76) (   3 H   1s  :    -0.76)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.69197 a.u.                                                                  
               (   1 O   2s  :     0.16) (   1 O   1p-1:     0.61) (   1 O   1p0 :    -0.76)                              
               (   2 H   1s  :    -0.88) (   3 H   1s  :     0.69)                                                        
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.9988271207 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.890314714542 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.890314747186    0.0000000000      0.00014197      0.00002435      0.00000000                
                  2       -74.890314758258   -0.0000000111      0.00001785      0.00000501      0.00020530                
                  3       -74.890314758311   -0.0000000001      0.00000391      0.00000087      0.00000745                
                  4       -74.890314758316   -0.0000000000      0.00000027      0.00000006      0.00000328                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.8903147583 a.u.                                              
               Electronic Energy                  :      -82.8891418791 a.u.                                              
               Nuclear Repulsion Energy           :        7.9988271207 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002694 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.25675 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21900 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.87) (   2 H   1s  :     0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.55250 a.u.                                                                  
               (   1 O   2s  :    -0.30) (   1 O   1p-1:     0.52) (   1 O   1p0 :    -0.34)                              
               (   2 H   1s  :     0.48) (   3 H   1s  :    -0.36)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40888 a.u.                                                                  
               (   1 O   2s  :     0.40) (   1 O   1p-1:    -0.50) (   1 O   1p0 :    -0.56)                              
               (   2 H   1s  :    -0.17) (   3 H   1s  :    -0.48)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38682 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.37290 a.u.                                                                  
               (   1 O   2s  :    -0.47) (   1 O   1p-1:    -0.22) (   1 O   1p0 :    -0.71)                              
               (   2 H   1s  :     0.24) (   3 H   1s  :     0.88)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.69116 a.u.                                                                  
               (   1 O   2s  :     0.56) (   1 O   1p-1:     0.81) (   1 O   1p0 :    -0.43)                              
               (   2 H   1s  :    -1.14) (   3 H   1s  :     0.21)                                                        
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)
          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.891396443     0.0e+00      3.9e-03          1   0:00:00
        2     -74.891459132    -6.3e-05      1.8e-03          1   0:00:00
        3     -74.891496417    -3.7e-05      9.6e-03          1   0:00:00
        4     -74.891582028    -8.6e-05      1.7e-03          1   0:00:00
        5     -74.891583404    -1.4e-06      1.0e-03          1   0:00:00
        6     -74.891583650    -2.5e-07      2.0e-04          1   0:00:00
        7     -74.891583662    -1.3e-08      4.0e-05          1   0:00:00
        8     -74.891583663    -6.9e-10      2.0e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.89158366315142
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99710 0.00290
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.25877 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21969 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.87) (   2 H   1s  :    -0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.55328 a.u.                                                                  
               (   1 O   2s  :    -0.30) (   1 O   1p-1:     0.52) (   1 O   1p0 :    -0.34)                              
               (   2 H   1s  :     0.48) (   3 H   1s  :    -0.36)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40960 a.u.                                                                  
               (   1 O   2s  :    -0.40) (   1 O   1p-1:     0.50) (   1 O   1p0 :     0.56)                              
               (   2 H   1s  :     0.17) (   3 H   1s  :     0.48)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.997 Energy:   -0.38696 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.003 Energy:    0.42335 a.u.                                                                  
               (   1 O   2s  :     0.65) (   1 O   1p-1:     0.53) (   1 O   1p0 :     0.48)                              
               (   2 H   1s  :    -0.68) (   3 H   1s  :    -0.72)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.63911 a.u.                                                                  
               (   1 O   2s  :     0.32) (   1 O   1p-1:     0.65) (   1 O   1p0 :    -0.68)                              
               (   2 H   1s  :    -0.94) (   3 H   1s  :     0.54)                                                        
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.5395732848 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.820748583254 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.820748697856    0.0000000000      0.00026411      0.00004348      0.00000000                
                  2       -74.820748745254   -0.0000000474      0.00008006      0.00002170      0.00039160                
                  3       -74.820748747305   -0.0000000021      0.00000755      0.00000219      0.00006846                
                  4       -74.820748747316   -0.0000000000      0.00000035      0.00000008      0.00000419                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.8207487473 a.u.                                              
               Electronic Energy                  :      -82.3603220321 a.u.                                              
               Nuclear Repulsion Energy           :        7.5395732848 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003470 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26675 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21338 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53488 a.u.                                                                  
               (   1 O   2s  :    -0.42) (   1 O   1p-1:     0.60) (   1 O   1p0 :    -0.25)                              
               (   2 H   1s  :     0.50) (   3 H   1s  :    -0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39126 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.37376 a.u.                                                                  
               (   1 O   2s  :    -0.28) (   1 O   1p-1:     0.38) (   1 O   1p0 :     0.61)                              
               (   3 H   1s  :     0.58)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.27265 a.u.                                                                  
               (   1 O   2s  :    -0.33) (   1 O   1p-1:    -0.19) (   1 O   1p0 :    -0.71)                              
               (   2 H   1s  :     0.16) (   3 H   1s  :     0.82)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67914 a.u.                                                                  
               (   1 O   2s  :     0.60) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.37)                              
               (   2 H   1s  :    -1.15)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.882527473     0.0e+00      1.1e-01          1   0:00:00
        2     -74.897532702    -1.5e-02      3.2e-02          1   0:00:00
        3     -74.899246178    -1.7e-03      1.8e-02          1   0:00:00
        4     -74.899382126    -1.4e-04      7.5e-03          1   0:00:00
        5     -74.899429106    -4.7e-05      2.5e-03          1   0:00:00
        6     -74.899434654    -5.5e-06      1.2e-03          1   0:00:00
        7     -74.899435327    -6.7e-07      3.8e-04          1   0:00:00
        8     -74.899435422    -9.4e-08      2.1e-04          1   0:00:00
        9     -74.899435440    -1.9e-08      5.8e-05          1   0:00:00
       10     -74.899435442    -1.1e-09      1.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 10 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.89943544157015
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.79682 0.20318
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27910 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21811 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53226 a.u.                                                                  
               (   1 O   2s  :     0.49) (   1 O   1p-1:    -0.68) (   2 H   1s  :    -0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40293 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.797 Energy:   -0.35223 a.u.                                                                  
               (   1 O   1p-1:     0.20) (   1 O   1p0 :     0.63) (   3 H   1s  :     0.64)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.203 Energy:    0.24232 a.u.                                                                  
               (   1 O   2s  :    -0.25) (   1 O   1p0 :    -0.75) (   3 H   1s  :     0.82)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66509 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.1860927234 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.752738771110 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.752739005792    0.0000000000      0.00039094      0.00006232      0.00000000                
                  2       -74.752739106095   -0.0000001003      0.00026997      0.00005995      0.00057506                
                  3       -74.752739127892   -0.0000000218      0.00000716      0.00000145      0.00021464                
                  4       -74.752739127904   -0.0000000000      0.00000087      0.00000015      0.00000558                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.01 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.7527391279 a.u.                                              
               Electronic Energy                  :      -81.9388318513 a.u.                                              
               Nuclear Repulsion Energy           :        7.1860927234 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000008685 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27266 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21267 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52948 a.u.                                                                  
               (   1 O   2s  :    -0.47) (   1 O   1p-1:     0.64) (   1 O   1p0 :    -0.20)                              
               (   2 H   1s  :     0.50) (   3 H   1s  :    -0.17)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39571 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.33381 a.u.                                                                  
               (   1 O   2s  :     0.18) (   1 O   1p-1:    -0.31) (   1 O   1p0 :    -0.63)                              
               (   3 H   1s  :    -0.63)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.19876 a.u.                                                                  
               (   1 O   2s  :     0.24) (   1 O   1p-1:     0.19) (   1 O   1p0 :     0.71)                              
               (   3 H   1s  :    -0.78)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67104 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.34)                              
               (   2 H   1s  :    -1.15)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.858330410     0.0e+00      1.1e-01          1   0:00:00
        2     -74.867278476    -8.9e-03      2.7e-02          1   0:00:00
        3     -74.867921857    -6.4e-04      8.3e-03          1   0:00:00
        4     -74.867949471    -2.8e-05      3.6e-03          1   0:00:00
        5     -74.867960562    -1.1e-05      1.6e-03          1   0:00:00
        6     -74.867961977    -1.4e-06      9.2e-04          1   0:00:00
        7     -74.867962386    -4.1e-07      3.0e-04          1   0:00:00
        8     -74.867962442    -5.6e-08      1.6e-04          1   0:00:00
        9     -74.867962453    -1.1e-08      4.5e-05          1   0:00:00
       10     -74.867962453    -6.2e-10      9.9e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 10 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.86796245337779
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.65377 0.34623
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.28242 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.22059 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53574 a.u.                                                                  
               (   1 O   2s  :     0.50) (   1 O   1p-1:    -0.67) (   2 H   1s  :    -0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40693 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.654 Energy:   -0.27901 a.u.                                                                  
               (   1 O   1p-1:    -0.22) (   1 O   1p0 :    -0.63) (   3 H   1s  :    -0.66)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.346 Energy:    0.14819 a.u.                                                                  
               (   1 O   2s  :     0.17) (   1 O   1p-1:     0.17) (   1 O   1p0 :     0.73)                              
               (   3 H   1s  :    -0.78)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65961 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.7857964358 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.665585583090 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.665585646980    0.0000000000      0.00020258      0.00003503      0.00000000                
                  2       -74.665585685136   -0.0000000382      0.00008519      0.00001498      0.00041646                
                  3       -74.665585686714   -0.0000000016      0.00002712      0.00000402      0.00003430                
                  4       -74.665585686970   -0.0000000003      0.00000166      0.00000040      0.00002448                
                  5       -74.665585686971   -0.0000000000      0.00000025      0.00000005      0.00000169                
                                                                                                                          
               *** SCF converged in 5 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.6655856870 a.u.                                              
               Electronic Energy                  :      -81.4513821228 a.u.                                              
               Nuclear Repulsion Energy           :        6.7857964358 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002543 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27543 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21368 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52865 a.u.                                                                  
               (   1 O   2s  :    -0.50) (   1 O   1p-1:     0.65) (   1 O   1p0 :    -0.19)                              
               (   2 H   1s  :     0.50)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40015 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.27895 a.u.                                                                  
               (   1 O   1p-1:    -0.26) (   1 O   1p0 :    -0.64) (   3 H   1s  :    -0.67)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.12283 a.u.                                                                  
               (   1 O   1p-1:    -0.20) (   1 O   1p0 :    -0.70) (   3 H   1s  :     0.74)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66396 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.31)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.837060098     0.0e+00      8.1e-02          1   0:00:00
        2     -74.841104832    -4.0e-03      1.8e-02          1   0:00:00
        3     -74.841290679    -1.9e-04      5.3e-03          1   0:00:00
        4     -74.841309522    -1.9e-05      2.3e-03          1   0:00:00
        5     -74.841318130    -8.6e-06      1.5e-03          1   0:00:00
        6     -74.841320093    -2.0e-06      8.3e-04          1   0:00:00
        7     -74.841320473    -3.8e-07      2.6e-04          1   0:00:00
        8     -74.841320525    -5.2e-08      1.2e-04          1   0:00:00
        9     -74.841320532    -7.3e-09      3.4e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 9 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.84132053218123
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.42192 0.57808
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27837 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21929 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53501 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.65) (   1 O   1p0 :     0.20)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40726 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.422 Energy:   -0.19529 a.u.                                                                  
               (   1 O   1p-1:     0.23) (   1 O   1p0 :     0.64) (   3 H   1s  :     0.68)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.578 Energy:    0.04821 a.u.                                                                  
               (   1 O   1p-1:     0.21) (   1 O   1p0 :     0.71) (   3 H   1s  :    -0.74)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65734 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.3284422371 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.569858224801 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.569858132117    0.0000000000      0.00521476      0.00150205      0.00000000                
                  2       -74.569865336724   -0.0000072046      0.00024001      0.00005100      0.00324201                
                  3       -74.569865350065   -0.0000000133      0.00002776      0.00000510      0.00013608                
                  4       -74.569865350828   -0.0000000008      0.00000342      0.00000063      0.00006083                
                  5       -74.569865350835   -0.0000000000      0.00000037      0.00000007      0.00000470                
                                                                                                                          
               *** SCF converged in 5 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.5698653508 a.u.                                              
               Electronic Energy                  :      -80.8983075880 a.u.                                              
               Nuclear Repulsion Energy           :        6.3284422371 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003666 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27117 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21343 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52855 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.65) (   1 O   1p0 :    -0.20)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40147 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.21527 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.66) (   3 H   1s  :    -0.69)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.05301 a.u.                                                                  
               (   1 O   1p-1:     0.21) (   1 O   1p0 :     0.68) (   3 H   1s  :    -0.72)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66097 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.826789080     0.0e+00      4.4e-02          1   0:00:00
        2     -74.827882512    -1.1e-03      7.9e-03          1   0:00:00
        3     -74.827938436    -5.6e-05      3.9e-03          1   0:00:00
        4     -74.827970507    -3.2e-05      2.4e-03          1   0:00:00
        5     -74.827978667    -8.2e-06      1.5e-03          1   0:00:00
        6     -74.827980172    -1.5e-06      3.8e-04          1   0:00:00
        7     -74.827980256    -8.4e-08      9.4e-05          1   0:00:00
        8     -74.827980264    -8.1e-09      4.4e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82798026388262
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.16464 0.83536
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27196 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21641 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53226 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.64) (   1 O   1p0 :     0.22)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40509 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.165 Energy:   -0.12123 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.65) (   3 H   1s  :    -0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.835 Energy:   -0.03467 a.u.                                                                  
               (   1 O   1p-1:     0.23) (   1 O   1p0 :     0.68) (   3 H   1s  :    -0.72)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65779 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.0212086638 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.519848212310 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.519794238781    0.0000000000      0.01475594      0.00439714      0.00000000                
                  2       -74.519853099827   -0.0000588610      0.00035523      0.00008942      0.00920391                
                  3       -74.519853129181   -0.0000000294      0.00002293      0.00000453      0.00018756                
                  4       -74.519853129690   -0.0000000005      0.00001197      0.00000241      0.00004132                
                  5       -74.519853129784   -0.0000000001      0.00000224      0.00000038      0.00001878                
                  6       -74.519853129786   -0.0000000000      0.00000067      0.00000017      0.00000313                
                                                                                                                          
               *** SCF converged in 6 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.5198531298 a.u.                                              
               Electronic Energy                  :      -80.5410617936 a.u.                                              
               Nuclear Repulsion Energy           :        6.0212086638 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000006685 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26576 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21181 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52740 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.65) (   1 O   1p0 :    -0.21)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40011 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.17962 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.67) (   3 H   1s  :     0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.01834 a.u.                                                                  
               (   1 O   1p-1:    -0.23) (   1 O   1p0 :    -0.67) (   3 H   1s  :     0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66180 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.825476170     0.0e+00      2.6e-02          1   0:00:00
        2     -74.825807829    -3.3e-04      3.7e-03          1   0:00:00
        3     -74.825821827    -1.4e-05      2.1e-03          1   0:00:00
        4     -74.825833843    -1.2e-05      1.2e-03          1   0:00:00
        5     -74.825835170    -1.3e-06      6.0e-04          1   0:00:00
        6     -74.825835384    -2.1e-07      9.8e-05          1   0:00:00
        7     -74.825835391    -7.3e-09      3.6e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 7 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82583539119172
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.05669 0.94331
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27047 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21572 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53158 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.64) (   1 O   1p0 :    -0.23)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40447 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.057 Energy:   -0.09334 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.66) (   3 H   1s  :    -0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.943 Energy:   -0.06478 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.67) (   3 H   1s  :    -0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65798 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 5.6344241715 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.084140230929 a.u. Time: 0.01 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.000503437703    0.0000000000      0.90532909      0.24131160      0.00000000                
                  2       -74.098394605837   -0.0978911681      0.59342893      0.16078738      0.18854771                
                  3       -74.127683290479   -0.0292886846      0.53156880      0.14521772      1.41709384                
                  4       -74.132164532108   -0.0044812416      0.51112112      0.13948385      0.01224419                
                  5       -74.132554495243   -0.0003899631      0.50908794      0.13886864      0.00122971                
                  6       -74.136771887308   -0.0042173921      0.48889199      0.13321685      0.01206759                
                  7       -74.120225737101    0.0165461502      0.49298083      0.13443188      1.41423531                
                  8       -74.102682049322    0.0175436878      0.63216124      0.17360742      1.41730265                
                  9       -74.044445014899    0.0582370344      0.78403566      0.21101671      1.43841747                
                 10       -73.490357821646    0.5540871933      1.55371332      0.40019657      1.57950526                
                 11       -73.954038175837   -0.4636803542      1.01876707      0.27054368      0.55911443                
                 12       -73.998169255684   -0.0441310798      0.91003147      0.24342939      1.41616309                
                 13       -73.974007961882    0.0241612938      0.97566365      0.25968019      1.41492158                
                 14       -74.090082896224   -0.1160749343      0.67628051      0.18615146      1.47238500                
                 15       -73.967426996066    0.1226559002      0.99037087      0.26345146      1.47513361                
                 16       -73.956402138139    0.0110248579      1.01368489      0.26913469      0.01851747                
                 17       -73.928217872630    0.0281842655      1.07026786      0.28349678      0.04339070                
                 18       -74.119718930542   -0.1915010579      0.56545406      0.15451225      1.47307599                
                 19       -74.116893558142    0.0028253724      0.57720235      0.15795005      0.00736138                
                 20       -74.149170822618   -0.0322772645      0.42354984      0.11489418      0.09178225                
                 21       -74.142417862247    0.0067529604      0.46034013      0.12512797      0.02187304                
                 22       -74.062607687629    0.0798101746      0.72621128      0.19569727      1.41987587                
                 23       -74.084035062883   -0.0214273753      0.65055501      0.17594777      0.04513344                
                 24       -74.126691001344   -0.0426559385      0.53577307      0.14632948      1.41982542                
                 25       -74.138958446754   -0.0122674454      0.47817108      0.13026965      0.03465839                
                 26       -73.980714435297    0.1582440115      0.95241576      0.25471855      1.44125674                
                 27       -73.987958974135   -0.0072445388      0.93559348      0.25042954      0.25914920                
                 28       -74.002386864791   -0.0144278907      0.90017695      0.24140916      0.21749589                
                 29       -74.124760828185   -0.1223739634      0.54424061      0.14871195      1.44213998                
                 30       -74.124276173149    0.0004846550      0.54634142      0.14930066      0.00129125                
                 31       -74.116851812719    0.0074243604      0.51000606      0.13891675      1.41514391                
                 32       -74.113058457707    0.0037933550      0.59258415      0.16229535      1.41644344                
                 33       -74.119718144175   -0.0066596865      0.56557393      0.15466154      0.01637631                
                 34       -74.129684781669   -0.0099666375      0.52444722      0.14307712      0.03276395                
                 35       -74.088694614755    0.0409901669      0.68099491      0.18746979      0.09727390                
                 36       -74.055617814793    0.0330768000      0.78168960      0.21646250      0.06403612                
                 37       -74.080737251396   -0.0251194366      0.70680314      0.19480893      0.04770721                
                 38       -74.077169051311    0.0035682001      0.71804610      0.19803831      0.00711637                
                 39       -74.108467349417   -0.0312982981      0.61065399      0.16744744      0.06692448                
                 40       -74.108902840872   -0.0004354915      0.60889775      0.16690421      0.00215028                
                 41       -73.923745878314    0.1851569626      1.07813465      0.28453863      1.48194724                
                 42       -73.977872448399   -0.0541265701      0.96604446      0.25627519      0.09592542                
                 43       -74.130742576699   -0.1528701283      0.48965788      0.13036781      0.44465762                
                 44       -73.974970537454    0.1557720392      0.96430340      0.25668041      1.40998270                
                 45       -74.145757604296   -0.1707870668      0.44260931      0.12011684      1.43947576                
                 46       -74.085215321200    0.0605422831      0.64644307      0.17493110      1.41581289                
                 47       -74.077508537574    0.0077067836      0.67472149      0.18227351      0.07424576                
                 48       -74.090323794361   -0.0128152568      0.62648235      0.16970486      0.15243630                
                 49       -74.131287021381   -0.0409632270      0.51544147      0.14061718      1.41767646                
                 50       -74.115444645506    0.0158423759      0.51686945      0.14073869      1.41468011                
                                                                                                                          
               *** SCF NOT converged in 50 iterations. Time: 0.16 sec.                                                    
                                                                                                                          
               *** Warning: SCF is not converged!                                                                         
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.825130439     0.0e+00      3.4e-02          1   0:00:00
        2     -74.825510361    -3.8e-04      3.4e-03          1   0:00:00
        3     -74.825514626    -4.3e-06      1.9e-04          1   0:00:00
        4     -74.825514636    -1.0e-08      7.0e-05          1   0:00:00
        5     -74.825514640    -3.7e-09      4.1e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 5 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82551463977956
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.00006 0.99994
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27024 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21562 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53149 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.64) (   1 O   1p0 :    -0.23)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40437 a.u.                                                                  
               (   1 O   1p-1:     0.33) (   1 O   1p0 :     0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.07896 a.u.                                                                  
               (   1 O   1p+1:    -0.71) (   3 H   1s  :    -0.71)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.07893 a.u.                                                                  
               (   1 O   1p+1:    -0.71) (   3 H   1s  :     0.71)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65799 a.u.                                                                  
               (   1 O   2s  :    -0.64) (   1 O   1p-1:    -0.83) (   1 O   1p0 :     0.29)                              
               (   2 H   1s  :     1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 5.4008697288 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -73.928853308431 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -73.978581312823    0.0000000000      0.90210952      0.23928520      0.00000000                
                  2       -74.088914398175   -0.1103330854      0.53233794      0.14416166      0.22125263                
                  3       -74.071543936890    0.0173704613      0.64859470      0.17787135      1.41924556                
                  4       -74.092318322593   -0.0207743857      0.51630213      0.14023817      1.41846667                
                  5       -74.110390124779   -0.0180718022      0.48813516      0.13269078      1.41427159                
                  6       -74.093273540118    0.0171165847      0.51162178      0.13898654      1.41425009                
                  7       -74.093731177703   -0.0004576376      0.50936430      0.13838913      0.00128042                
                  8       -74.093975721121   -0.0002445434      0.50815336      0.13806842      0.00068614                
                  9       -74.094136567588   -0.0001608465      0.50735513      0.13785695      0.00045210                
                 10       -74.094254293229   -0.0001177256      0.50677004      0.13770192      0.00033131                
                 11       -74.093421694271    0.0008325990      0.51088482      0.13878503      0.00234652                
                 12       -74.076736422357    0.0166852719      0.62951282      0.17231048      1.41744734                
                 13       -74.093989062408   -0.0172526401      0.50807747      0.13804005      1.41734129                
                 14       -74.094214888656   -0.0002258262      0.50696143      0.13774772      0.00064202                
                 15       -74.094397893712   -0.0001830051      0.50605105      0.13750659      0.00051583                
                 16       -74.081968867819    0.0124290259      0.61033903      0.16704653      1.41650338                
                 17       -74.088654929410   -0.0066860616      0.58422326      0.15967018      0.01590009                
                 18       -74.110283866924   -0.0216289375      0.48867866      0.13285857      0.05734273                
                 19       -74.094550267355    0.0157335996      0.50528968      0.13730360      1.41423023                
                 20       -74.094613310682   -0.0000630433      0.50497545      0.13722033      0.00023171                
                 21       -74.094126199839    0.0004871108      0.50740275      0.13786288      0.00170869                
                 22       -74.094770089999   -0.0006438902      0.50419251      0.13701290      0.00210996                
                 23       -74.094827661452   -0.0000575715      0.50390618      0.13693806      0.00016791                
                 24       -74.094904069732   -0.0000764083      0.50352383      0.13683680      0.00021695                
                 25       -74.094962735859   -0.0000586661      0.50322999      0.13675894      0.00016674                
                 26       -74.095007158065   -0.0000444222      0.50300735      0.13669995      0.00012668                
                 27       -74.094927000037    0.0000801580      0.50340826      0.13680560      0.00022849                
                 28       -74.109580921781   -0.0146539217      0.49212496      0.13382850      1.41423519                
                 29       -74.109141509328    0.0004394125      0.49426160      0.13442540      0.00140959                
                 30       -74.109241540024   -0.0001000307      0.49377885      0.13429038      0.00163346                
                 31       -74.112507085668   -0.0032655456      0.49675803      0.13298591      0.06211278                
                 32       -74.052611022082    0.0598960636      0.71185775      0.19589390      0.14568365                
                 33       -74.095530502210   -0.0429194801      0.50070348      0.13605473      1.42109419                
                 34       -74.098882464747   -0.0033519625      0.50724727      0.13530591      0.05927841                
                 35       -74.247908181313   -0.1490257166      0.63859099      0.12763749      0.42238969                
                 36       -74.327981639477   -0.0800734582      0.57801332      0.12269769      0.98612042                
                 37       -74.096772113118    0.2312095264      0.51034916      0.13693138      1.29749805                
                 38       -74.102731559341   -0.0059594462      0.54219987      0.13909026      0.17889457                
                 39       -74.269288051190   -0.1665564918      0.61950124      0.12532466      1.36002208                
                 40       -74.215526791616    0.0537612596      0.61571438      0.11498914      0.85812576                
                 41       -74.261797797290   -0.0462710057      0.63667165      0.12906946      1.11996499                
                 42       -74.093785896289    0.1680119010      0.50951495      0.13837626      0.52015790                
                 43       -74.092756709334    0.0010291870      0.51685561      0.14007224      0.01436458                
                 44       -74.110065748808   -0.0173090395      0.48986423      0.13318666      1.41401421                
                 45       -74.272909944352   -0.1628441955      0.63320830      0.12965318      1.30867082                
                 46       -74.444071986121   -0.1711620418      0.26318566      0.05896422      0.70922429                
                 47       -74.103230668036    0.3408413181      0.51679414      0.13456255      1.17745578                
                 48       -74.120692843717   -0.0174621757      0.54908513      0.13125143      0.08463799                
                 49       -74.197980778758   -0.0772879350      0.62924962      0.11605533      0.20582962                
                 50       -74.095793777378    0.1021870014      0.50275087      0.13623305      0.41445816                
                                                                                                                          
               *** SCF NOT converged in 50 iterations. Time: 0.19 sec.                                                    
                                                                                                                          
               *** Warning: SCF is not converged!                                                                         
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.825492533     0.0e+00      7.5e-03          1   0:00:00
        2     -74.825514535    -2.2e-05      7.6e-04          1   0:00:00
        3     -74.825514784    -2.5e-07      3.7e-05          1   0:00:00
        4     -74.825514784    -4.6e-10      9.0e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 4 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82551478434038
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.00000 1.00000
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27024 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21562 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53149 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.64) (   1 O   1p0 :     0.23)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40437 a.u.                                                                  
               (   1 O   1p-1:    -0.33) (   1 O   1p0 :    -0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.07979 a.u.                                                                  
               (   1 O   1p+1:     0.71) (   3 H   1s  :    -0.71)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.07979 a.u.                                                                  
               (   1 O   1p+1:     0.71) (   3 H   1s  :     0.71)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65799 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
plt.figure(figsize=(6,4))
plt.title('Energy during O-H dissociation')
x = np.array(distlist)
y = np.array(E_FCI)
z = np.array(E_hf)
zz = np.array(E_CASSCF)
plt.plot(x,y, label='FullCI')
plt.plot(x,z, label='RHF')
plt.plot(x,zz, label='CASSCF')
plt.legend()
plt.tight_layout(); plt.show()
../../_images/mcscf_11_0.png

The result looks a bit disappointing. On one side, the MCSCF converges without major issue (unlike Hartree-Fock) and indeed approaches the FCI result at long distances. However, at short distances it did no better than HF, resulting in a weird transition between the two zones.

To understand why, let’s visualize the Hartree-Fock orbitals for a distance of 1.1 Å.

#Run again the 1.1 Å Hartree-Fock
mol_str = mol_template.replace("OHdist", "1.1")
molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
basis = vlx.MolecularBasis.read(molecule, "STO-3G")
scfdrv.compute(molecule, basis)
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 8.6203186612 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.947250973879 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.947250981138    0.0000000000      0.00006046      0.00001095      0.00000000                
                  2       -74.947250982569   -0.0000000014      0.00001394      0.00000251      0.00006130                
                  3       -74.947250982655   -0.0000000001      0.00000159      0.00000036      0.00001805                
                  4       -74.947250982655   -0.0000000000      0.00000011      0.00000002      0.00000116                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.9472509827 a.u.                                              
               Electronic Energy                  :      -83.5675696438 a.u.                                              
               Nuclear Repulsion Energy           :        8.6203186612 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000001106 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.24331 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.23684 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.85) (   2 H   1s  :    -0.18)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.59041 a.u.                                                                  
               (   1 O   1p-1:    -0.41) (   1 O   1p0 :     0.44) (   2 H   1s  :    -0.45)                              
               (   3 H   1s  :     0.43)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.43151 a.u.                                                                  
               (   1 O   2s  :    -0.49) (   1 O   1p-1:     0.60) (   1 O   1p0 :     0.49)                              
               (   2 H   1s  :     0.24) (   3 H   1s  :     0.35)                                                        
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.38490 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.50463 a.u.                                                                  
               (   1 O   2s  :    -0.69) (   1 O   1p-1:    -0.34) (   1 O   1p0 :    -0.66)                              
               (   2 H   1s  :     0.44) (   3 H   1s  :     0.94)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.71372 a.u.                                                                  
               (   1 O   2s  :    -0.41) (   1 O   1p-1:    -0.76) (   1 O   1p0 :     0.58)                              
               (   2 H   1s  :     1.08) (   3 H   1s  :    -0.41)                                                        
                                                                                                                          
viewer = mtp.OrbitalViewer()
viewer.plot(molecule, basis, scfdrv.mol_orbs)

This highlights one of the main difficulties in MCSCF. It is not enough to provide the number of active orbitals, it is essential to provide the right ones. By default, our CAS(2,2) includes the HOMO and LUMO of our starting HF orbitals, but at 1.1 Å, the HOMO is an oxygen lone pair, not the \(\sigma\). We can fix this by explicitely requesting the HOMO-1 in this case.

We could visualize the starting orbitals for every geometry, but an easier alternative is to visualize a single structure, and then use these orbitals and active space as a starting point for all the other structures. The hope is that the active space will be stable over the entire scan (similarly for optimization or dynamics).

Generally, the stronger the correlation, the more stable is the active space. Thus, here, the best strategy is to start from the long distances and then scan backwards.

E_CASSCF=[]

#Initialise our first guess to 2Å
mol_str = mol_template.replace("OHdist", "2")
molecule = vlx.Molecule.read_str(mol_str, units='angstrom')
basis = vlx.MolecularBasis.read(molecule,"STO-3G")
scfdrv.compute(molecule, basis)

space = mtp.OrbSpace(molecule, scfdrv.mol_orbs)
space.CAS(2,2)

#Scan over O-H distances in reverse order
for dist in distlist[::-1]:
    mol_str = mol_template.replace("OHdist", str(dist))
    molecule = vlx.Molecule.read_str(mol_str, units='angstrom')

    Mcscfdrv.compute(molecule, basis, space)
    E_CASSCF.append(Mcscfdrv.getEnergy(0)-E_H_hf-E_OH_hf)

E_CASSCF=E_CASSCF[::-1] #Reorder the energies
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 6.7857964358 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.665585583090 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.665585646980    0.0000000000      0.00020258      0.00003503      0.00000000                
                  2       -74.665585685136   -0.0000000382      0.00008519      0.00001498      0.00041646                
                  3       -74.665585686714   -0.0000000016      0.00002712      0.00000402      0.00003430                
                  4       -74.665585686970   -0.0000000003      0.00000166      0.00000040      0.00002448                
                  5       -74.665585686971   -0.0000000000      0.00000025      0.00000005      0.00000169                
                                                                                                                          
               *** SCF converged in 5 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.6655856870 a.u.                                              
               Electronic Energy                  :      -81.4513821228 a.u.                                              
               Nuclear Repulsion Energy           :        6.7857964358 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000002543 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27543 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21368 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52865 a.u.                                                                  
               (   1 O   2s  :     0.50) (   1 O   1p-1:    -0.65) (   1 O   1p0 :     0.19)                              
               (   2 H   1s  :    -0.50)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40015 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.27895 a.u.                                                                  
               (   1 O   1p-1:     0.26) (   1 O   1p0 :     0.64) (   3 H   1s  :     0.67)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.12283 a.u.                                                                  
               (   1 O   1p-1:     0.20) (   1 O   1p0 :     0.70) (   3 H   1s  :    -0.74)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66396 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.31)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.814517828     0.0e+00      1.3e-01          1   0:00:00
        2     -74.825176298    -1.1e-02      2.1e-02          1   0:00:00
        3     -74.825391905    -2.2e-04      7.4e-03          1   0:00:00
        4     -74.825474393    -8.2e-05      4.8e-03          1   0:00:00
        5     -74.825507822    -3.3e-05      3.6e-03          1   0:00:00
        6     -74.825513926    -6.1e-06      1.2e-03          1   0:00:00
        7     -74.825514699    -7.7e-07      3.3e-04          1   0:00:00
        8     -74.825514778    -7.9e-08      1.4e-04          1   0:00:00
        9     -74.825514788    -1.0e-08      3.7e-05          1   0:00:00
       10     -74.825514789    -9.8e-10      1.1e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 10 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82551478900174
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.00018 0.99982
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27024 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21562 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53149 a.u.                                                                  
               (   1 O   2s  :    -0.51) (   1 O   1p-1:     0.64) (   1 O   1p0 :    -0.23)                              
               (   2 H   1s  :     0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40437 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.08031 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.67) (   3 H   1s  :    -0.71)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.000 Energy:   -0.08022 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.67) (   3 H   1s  :     0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65799 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.825517341     0.0e+00      5.8e-04          1   0:00:00
        2     -74.825517491    -1.5e-07      6.7e-05          1   0:00:00
        3     -74.825517493    -1.9e-09      3.2e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 3 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.8255174925583
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.00464 0.99536
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27024 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21562 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53149 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.64) (   1 O   1p0 :     0.23)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40437 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.005 Energy:   -0.08097 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.67) (   3 H   1s  :     0.71)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.995 Energy:   -0.07875 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.67) (   3 H   1s  :    -0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65799 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.825819306     0.0e+00      5.3e-03          1   0:00:00
        2     -74.825835050    -1.6e-05      7.0e-04          1   0:00:00
        3     -74.825835368    -3.2e-07      1.0e-04          1   0:00:00
        4     -74.825835380    -1.2e-08      5.8e-05          1   0:00:00
        5     -74.825835392    -1.2e-08      3.9e-05          1   0:00:00
        6     -74.825835392    -7.3e-10      1.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 6 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82583539224215
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.05669 0.94331
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27047 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21572 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53158 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.64) (   1 O   1p0 :     0.23)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40447 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.057 Energy:   -0.09334 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.66) (   3 H   1s  :     0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.943 Energy:   -0.06478 a.u.                                                                  
               (   1 O   1p-1:     0.24) (   1 O   1p0 :     0.67) (   3 H   1s  :    -0.71)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65798 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.827907819     0.0e+00      1.1e-02          1   0:00:00
        2     -74.827975682    -6.8e-05      1.9e-03          1   0:00:00
        3     -74.827978907    -3.2e-06      6.0e-04          1   0:00:00
        4     -74.827979678    -7.7e-07      4.6e-04          1   0:00:00
        5     -74.827980226    -5.5e-07      2.2e-04          1   0:00:00
        6     -74.827980263    -3.7e-08      5.5e-05          1   0:00:00
        7     -74.827980265    -1.8e-09      4.4e-06          1   0:00:00
                                                                                                                          
** Convergence reached in 7 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.82798026508473
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.16464 0.83536
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27197 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21641 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53226 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.64) (   1 O   1p0 :     0.22)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40509 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.165 Energy:   -0.12123 a.u.                                                                  
               (   1 O   1p-1:    -0.24) (   1 O   1p0 :    -0.65) (   3 H   1s  :    -0.70)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.835 Energy:   -0.03467 a.u.                                                                  
               (   1 O   1p-1:    -0.23) (   1 O   1p0 :    -0.68) (   3 H   1s  :     0.72)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65779 a.u.                                                                  
               (   1 O   2s  :     0.64) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.29)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.840703453     0.0e+00      2.9e-02          1   0:00:00
        2     -74.841179001    -4.8e-04      8.5e-03          1   0:00:00
        3     -74.841271315    -9.2e-05      4.0e-03          1   0:00:00
        4     -74.841307191    -3.6e-05      2.9e-03          1   0:00:00
        5     -74.841319643    -1.2e-05      1.1e-03          1   0:00:00
        6     -74.841320497    -8.5e-07      2.2e-04          1   0:00:00
        7     -74.841320530    -3.3e-08      5.9e-05          1   0:00:00
        8     -74.841320532    -2.4e-09      3.0e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.84132053225392
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.42191 0.57809
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27837 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21929 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53501 a.u.                                                                  
               (   1 O   2s  :     0.51) (   1 O   1p-1:    -0.65) (   1 O   1p0 :     0.20)                              
               (   2 H   1s  :    -0.51)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40726 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.422 Energy:   -0.19530 a.u.                                                                  
               (   1 O   1p-1:    -0.23) (   1 O   1p0 :    -0.64) (   3 H   1s  :    -0.68)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.578 Energy:    0.04821 a.u.                                                                  
               (   1 O   1p-1:    -0.21) (   1 O   1p0 :    -0.71) (   3 H   1s  :     0.74)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65734 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.866784720     0.0e+00      3.9e-02          1   0:00:00
        2     -74.867537536    -7.5e-04      1.5e-02          1   0:00:00
        3     -74.867871403    -3.3e-04      7.6e-03          1   0:00:00
        4     -74.867945833    -7.4e-05      4.2e-03          1   0:00:00
        5     -74.867961788    -1.6e-05      9.7e-04          1   0:00:00
        6     -74.867962390    -6.0e-07      2.6e-04          1   0:00:00
        7     -74.867962443    -5.3e-08      1.3e-04          1   0:00:00
        8     -74.867962453    -1.0e-08      4.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.86796245264348
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.65377 0.34623
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.28242 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.22059 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53574 a.u.                                                                  
               (   1 O   2s  :    -0.50) (   1 O   1p-1:     0.67) (   2 H   1s  :     0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40693 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.654 Energy:   -0.27901 a.u.                                                                  
               (   1 O   1p-1:    -0.22) (   1 O   1p0 :    -0.63) (   3 H   1s  :    -0.66)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.346 Energy:    0.14819 a.u.                                                                  
               (   1 O   2s  :    -0.17) (   1 O   1p-1:    -0.17) (   1 O   1p0 :    -0.73)                              
               (   3 H   1s  :     0.78)                                                                                  
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.65961 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.898353116     0.0e+00      4.3e-02          1   0:00:00
        2     -74.899027504    -6.7e-04      1.6e-02          1   0:00:00
        3     -74.899388088    -3.6e-04      8.4e-03          1   0:00:00
        4     -74.899429393    -4.1e-05      3.5e-03          1   0:00:00
        5     -74.899435163    -5.8e-06      5.5e-04          1   0:00:00
        6     -74.899435386    -2.2e-07      2.5e-04          1   0:00:00
        7     -74.899435437    -5.1e-08      1.1e-04          1   0:00:00
        8     -74.899435441    -4.4e-09      2.6e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.89943544138077
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.79682 0.20318
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27910 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21811 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53226 a.u.                                                                  
               (   1 O   2s  :    -0.49) (   1 O   1p-1:     0.68) (   2 H   1s  :     0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40293 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.797 Energy:   -0.35224 a.u.                                                                  
               (   1 O   1p-1:    -0.20) (   1 O   1p0 :    -0.63) (   3 H   1s  :    -0.64)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.203 Energy:    0.24232 a.u.                                                                  
               (   1 O   2s  :    -0.25) (   1 O   1p0 :    -0.75) (   3 H   1s  :     0.82)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66510 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.938756602     0.0e+00      6.0e-02          1   0:00:00
        2     -74.939681388    -9.2e-04      2.2e-02          1   0:00:00
        3     -74.940128796    -4.5e-04      1.0e-02          1   0:00:00
        4     -74.940161093    -3.2e-05      3.4e-03          1   0:00:00
        5     -74.940163974    -2.9e-06      4.1e-04          1   0:00:00
        6     -74.940164153    -1.8e-07      2.9e-04          1   0:00:00
        7     -74.940164205    -5.2e-08      1.0e-04          1   0:00:00
        8     -74.940164208    -2.3e-09      2.0e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.94016420750653
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.89831 0.10169
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26774 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21102 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.89) (   2 H   1s  :    -0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.52451 a.u.                                                                  
               (   1 O   2s  :    -0.48) (   1 O   1p-1:     0.70) (   2 H   1s  :     0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39608 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.898 Energy:   -0.43884 a.u.                                                                  
               (   1 O   1p-1:    -0.18) (   1 O   1p0 :    -0.64) (   3 H   1s  :    -0.61)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.102 Energy:    0.36290 a.u.                                                                  
               (   1 O   2s  :    -0.35) (   1 O   1p0 :    -0.78) (   3 H   1s  :     0.90)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67381 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.975431652     0.0e+00      8.0e-02          1   0:00:00
        2     -74.976454845    -1.0e-03      2.7e-02          1   0:00:00
        3     -74.976872651    -4.2e-04      1.2e-02          1   0:00:00
        4     -74.976897736    -2.5e-05      3.1e-03          1   0:00:00
        5     -74.976899246    -1.5e-06      2.5e-04          1   0:00:00
        6     -74.976899365    -1.2e-07      2.8e-04          1   0:00:00
        7     -74.976899403    -3.9e-08      9.9e-05          1   0:00:00
        8     -74.976899405    -2.0e-09      2.0e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.97689940547379
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.95549 0.04451
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.25069 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.19720 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.22)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.51524 a.u.                                                                  
               (   1 O   2s  :     0.47) (   1 O   1p-1:    -0.71) (   2 H   1s  :    -0.48)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39058 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.955 Energy:   -0.54572 a.u.                                                                  
               (   1 O   1p-1:    -0.16) (   1 O   1p0 :    -0.64) (   3 H   1s  :    -0.58)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.045 Energy:    0.52130 a.u.                                                                  
               (   1 O   2s  :    -0.50) (   1 O   1p0 :    -0.82) (   3 H   1s  :     1.02)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.68245 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.31)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.977881532     0.0e+00      7.9e-02          1   0:00:00
        2     -74.978501027    -6.2e-04      2.4e-02          1   0:00:00
        3     -74.978729454    -2.3e-04      1.2e-02          1   0:00:00
        4     -74.978742693    -1.3e-05      2.5e-03          1   0:00:00
        5     -74.978743363    -6.7e-07      1.5e-04          1   0:00:00
        6     -74.978743407    -4.4e-08      1.9e-04          1   0:00:00
        7     -74.978743424    -1.7e-08      7.8e-05          1   0:00:00
        8     -74.978743426    -1.6e-09      2.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.9787434256807
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.97752 0.02248
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23823 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.17841 a.u.                                                                  
               (   1 O   1s  :     0.23) (   1 O   2s  :    -0.87) (   1 O   1p0 :     0.17)                              
               (   2 H   1s  :    -0.24)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.51005 a.u.                                                                  
               (   1 O   2s  :     0.47) (   1 O   1p-1:    -0.72) (   2 H   1s  :    -0.47)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39112 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.978 Energy:   -0.64899 a.u.                                                                  
               (   1 O   1p0 :    -0.64) (   3 H   1s  :    -0.54)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.022 Energy:    0.67468 a.u.                                                                  
               (   1 O   2s  :    -0.66) (   1 O   1p0 :    -0.87) (   3 H   1s  :     1.16)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.68604 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.31)                              
               (   2 H   1s  :    -1.17)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.967808969     0.0e+00      3.2e-02          1   0:00:00
        2     -74.967891786    -8.3e-05      8.9e-03          1   0:00:00
        3     -74.967918058    -2.6e-05      4.7e-03          1   0:00:00
        4     -74.967919230    -1.2e-06      1.1e-03          1   0:00:00
        5     -74.967919289    -5.9e-08      8.2e-05          1   0:00:00
        6     -74.967919291    -1.5e-09      3.4e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 6 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.96791929100307
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.98225 0.01775
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23511 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.16974 a.u.                                                                  
               (   1 O   1s  :    -0.23) (   1 O   2s  :     0.86) (   1 O   1p0 :    -0.18)                              
               (   2 H   1s  :     0.25)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.50906 a.u.                                                                  
               (   1 O   2s  :     0.46) (   1 O   1p-1:    -0.73) (   2 H   1s  :    -0.46)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39277 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.982 Energy:   -0.68965 a.u.                                                                  
               (   1 O   1p0 :    -0.65) (   3 H   1s  :    -0.53)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.018 Energy:    0.73358 a.u.                                                                  
               (   1 O   2s  :    -0.72) (   1 O   1p0 :    -0.89) (   3 H   1s  :     1.23)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.68623 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.32)                              
               (   2 H   1s  :    -1.17)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.914850659     0.0e+00      7.3e-02          1   0:00:00
        2     -74.915201793    -3.5e-04      1.9e-02          1   0:00:00
        3     -74.915312231    -1.1e-04      1.1e-02          1   0:00:00
        4     -74.915321192    -9.0e-06      2.5e-03          1   0:00:00
        5     -74.915321681    -4.9e-07      2.0e-04          1   0:00:00
        6     -74.915321711    -3.0e-08      1.3e-04          1   0:00:00
        7     -74.915321723    -1.1e-08      9.4e-05          1   0:00:00
        8     -74.915321725    -2.6e-09      4.3e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 8 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.91532172546813
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.98905 0.01095
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23258 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.14891 a.u.                                                                  
               (   1 O   1s  :    -0.23) (   1 O   2s  :     0.85) (   1 O   1p0 :    -0.21)                              
               (   2 H   1s  :     0.27)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.50872 a.u.                                                                  
               (   1 O   2s  :     0.46) (   1 O   1p-1:    -0.74) (   2 H   1s  :    -0.44)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39913 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.989 Energy:   -0.78170 a.u.                                                                  
               (   1 O   1p0 :    -0.65) (   3 H   1s  :    -0.50)                                                        
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.011 Energy:    0.86377 a.u.                                                                  
               (   1 O   2s  :    -0.89) (   1 O   1p0 :    -0.94) (   3 H   1s  :     1.39)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.68421 a.u.                                                                  
               (   1 O   2s  :     0.62) (   1 O   1p-1:     0.81) (   1 O   1p0 :    -0.33)                              
               (   2 H   1s  :    -1.17)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)
          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.792754964     0.0e+00      8.6e-02          1   0:00:00
        2     -74.793189220    -4.3e-04      2.1e-02          1   0:00:00
        3     -74.793306687    -1.2e-04      1.2e-02          1   0:00:00
        4     -74.793321534    -1.5e-05      2.8e-03          1   0:00:00
        5     -74.793322460    -9.3e-07      3.4e-04          1   0:00:00
        6     -74.793322597    -1.4e-07      3.3e-04          1   0:00:00
        7     -74.793322669    -7.3e-08      3.1e-04          1   0:00:00
        8     -74.793322691    -2.2e-08      1.4e-04          1   0:00:00
        9     -74.793322695    -3.6e-09      3.8e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 9 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.79332269491103
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99334 0.00666
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.23959 a.u.                                                                  
               (   1 O   1s  :    -0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.12671 a.u.                                                                  
               (   1 O   1s  :    -0.22) (   1 O   2s  :     0.83) (   1 O   1p0 :    -0.24)                              
               (   2 H   1s  :     0.29)                                                                                  
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.51090 a.u.                                                                  
               (   1 O   2s  :    -0.46) (   1 O   1p-1:     0.75) (   1 O   1p0 :     0.17)                              
               (   2 H   1s  :     0.41)                                                                                  
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.41073 a.u.                                                                  
               (   1 O   1p+1:     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.993 Energy:   -0.88664 a.u.                                                                  
               (   1 O   1p0 :     0.66) (   2 H   1s  :    -0.16) (   3 H   1s  :     0.46)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.007 Energy:    1.00930 a.u.                                                                  
               (   1 O   2s  :     1.11) (   1 O   1p0 :     1.01) (   3 H   1s  :    -1.62)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67709 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.81) (   1 O   1p0 :    -0.33)                              
               (   2 H   1s  :    -1.18)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
plt.figure(figsize=(6,4))
plt.title('Energy during O-H dissociation')
x = np.array(distlist)
y = np.array(E_FCI)
z = np.array(E_hf)
zz = np.array(E_CASSCF)
plt.plot(x, y, label='FullCI')
plt.plot(x, z, label='RHF')
plt.plot(x, zz, label='CASSCF')
plt.legend()
plt.tight_layout(); plt.show()
../../_images/mcscf_17_0.png

We now have a smooth curve that is nearly as good (in this minimal basis case where correlation outside of the active space is limited) as the full CI.

Overall, it is always a good idea to check the starting orbitals you provide, as well as the final orbitals (after convergence).

Theory#

In order to understand the theory below, it is recommended to first read the chapter on Hartree-Fock and Configuration Interaction as this section borrows extensively from both.

The MCSCF wavefunction contains both CI and orbital parameters and can be written as

\[ | \Psi_{\text{MCSCF}} \rangle = e^{-\hat{\kappa}} \Big(\sum_I c_I | \mathbf{I} \rangle\Big) \]

with \(\hat{\kappa}\) the orbital rotation operator

\[ \hat{\kappa} = \sum_{p<q} \kappa_{pq} \big(\hat{E}_{pq} - \hat{E}_{qp}\big) \]

It is often simpler to treat the optimization as two separate problems, an optimization of the CI coefficients followed by an optimization of the orbitals. Doing so means neglecting the coupling between the two occuring in the Hessian (\(\frac{\partial^2 E}{\partial c_I \partial \kappa_{pq}}\)), and the method is thus “first order”.

The CI optimization can be done following the standard CI techniques seen in a previous chapter. However, the orbital optimization needs more inspection. The general expression of the orbital derivative is:

\[ \frac{\partial E}{\partial \kappa_{pq}} = 2 (F_{pq} - F_{qp}) \]

with

\[ F_{pq} = \sum_r D_{pr} h_{rq} + 2\sum_{rst} \Gamma_{prst}(rq|st) \]

with \(\mathbf{D}\) and \(\boldsymbol{\Gamma}\) being the one and two-particle density matrices, respectively. For a Hartree-Fock wavefunction, the one-particle density is diagonal with an occupation number of 2 for all occupied orbitals and \(\Gamma_{pqrs} = D_{pq}D_{rs} - \frac{1}{2} D_{pr}D_{qs}\) , and the equation then simplifies to the usual Fock matrix:

\[ F_{pq}^{\mathrm{HF}} = 2h_{pq} + 2\sum_{s} 2(pq|ss) - (ps|qs) \]

The MCSCF matrix is more complicated, and we can see two cases depending on if \(p\) is inactive or active:

\[ F_{iq} = 2h_{iq} + 2\sum_j 2(iq|jj) - (ij|qj) + \sum_{tu} D_{tu} [2 (iq|tu) − (it|qu)] \]

and

\[ F_{tq} = \sum_u D_{tu} [h_{uq} + \sum_j 2(uq|jj) - (uj|qj)] + 2\sum_{uvw} \Gamma_{tuvw}(uq|vw) \]

where we have used the indices \(i, j\) for inactive orbitals, \(t,u, v, w\) for active and \(a,b\) for virtual. The matrices \(D_{tu}\) and \(\Gamma_{tuvw}\) are the active one and two-particle density matrices computed by the CI code.

By defining the inactive Fock matrix \(F^\mathrm{I}_{pq} = h_{pq} + \sum_j 2(pq|jj) - (pj|qj)\), we can simplify these expressions somewhat

\[ F_{iq} = 2F^\mathrm{I}_{iq} + \sum_{tu} D_{tu} [2 (iq|tu) − (it|qu)] \]

and

\[ F_{tq} = \sum_u D_{tu} F^\mathrm{I}_{uq} + 2\sum_{uvw} \Gamma_{tuvw}(uq|vw) \]

Since this matrix is analogous to the HF Fock matrix, it is usually called the effective Fock matrix.

In HF, the Fock matrix is diagonalized, and it is easy to see how doing so indeed sets the gradient \(2(F_{pq}-F_{qp})\) to 0. However, the MCSCF matrix is not symmetric and cannot in general be diagonalized. Note that the inactive-inactive block looks very similar to a Hartree-Fock Fock matrix and can be diagonalized, which defines the orbital energies for the inactive orbitals.

Since we cannot diagonalize the MCSCF Fock matrix, we need to find a different way to set the gradient to 0. Different techniques exist, but one of the most popular is to use the Newton method.

The Newton method is a second order method, which means it makes use of the second derivatives to improve the rate of convergence. According to this method, the optimal displacement \(\mathbf{X}\) to fulfill convergence is given by

\[ \mathbf{X} = \mathbf{H}^{-1} \mathbf{G} \]

with the Hessian \(\mathbf{H}\) and gradient \(\mathbf{G}\).

However, even approximate second derivatives can lead to fast convergence of the method, and as mentioned above, here we will neglect the coupling between CI and orbital parameters that occur in a full Newton algorithm. Similarly, the exact orbital-orbital Hessian includes integrals in the molecular orbital (MO) basis with inactive and virtual indices. Since the transformation to the MO basis is expensive, we want to restrict it to only active indices (which are needed for the CI). It is thus customary to use an approximation even for the orbital-orbital Hessian which uses only matrix elements already used for the gradients and is diagonal:

\[ H_{ia}=2 F^\mathrm{I}_{aa} - 2 F^\mathrm{I}_{ii} \]
\[ H_{ta}=D_{tt} F^\mathrm{I}_{aa} - 2 F_{tt} \]
\[ H_{it}=2F^\mathrm{I}_{tt}- 2 F^\mathrm{I}_{ii} + D_{tt} F^\mathrm{I}_{ii} - 2 F_{tt} \]

Implementation#

With all the equations set up, we can now implement a MCSCF. We are going to make use of the CI module in MultiPsi (a CI implementation is suggested in a previous section) as well as the integrals modules of Veloxchem.

Let’s consider a moderately stretched water molecule with starting orbitals computed at the HF level.

water_stretched = """
O 0.0000 0.0000  0.0000
H 0.0000 0.8957 -0.3167
H 0.0000 0.0000  1.5
"""
molecule = vlx.Molecule.read_str(water_stretched, units='angstrom')
scfdrv = vlx.ScfRestrictedDriver()
scfdrv.compute(molecule, basis)
                                                                                                                          
                                            Self Consistent Field Driver Setup                                            
                                           ====================================                                           
                                                                                                                          
                   Wave Function Model             : Spin-Restricted Hartree-Fock                                         
                   Initial Guess Model             : Superposition of Atomic Densities                                    
                   Convergence Accelerator         : Two Level Direct Inversion of Iterative Subspace                     
                   Max. Number of Iterations       : 50                                                                   
                   Max. Number of Error Vectors    : 10                                                                   
                   Convergence Threshold           : 1.0e-06                                                              
                   ERI Screening Scheme            : Cauchy Schwarz + Density                                             
                   ERI Screening Mode              : Dynamic                                                              
                   ERI Screening Threshold         : 1.0e-12                                                              
                   Linear Dependence Threshold     : 1.0e-06                                                              
                                                                                                                          
* Info * Nuclear repulsion energy: 7.5395732848 a.u.                                                                      
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * SAD initial guess computed in 0.00 sec.                                                                          
                                                                                                                          
* Info * Starting Reduced Basis SCF calculation...                                                                        
* Info * ...done. SCF energy in reduced basis set: -74.820748583254 a.u. Time: 0.02 sec.                                  
                                                                                                                          
* Info * Overlap matrix computed in 0.00 sec.                                                                             
                                                                                                                          
* Info * Kinetic energy matrix computed in 0.00 sec.                                                                      
                                                                                                                          
* Info * Nuclear potential matrix computed in 0.00 sec.                                                                   
                                                                                                                          
* Info * Orthogonalization matrix computed in 0.00 sec.                                                                   
                                                                                                                          
                                                                                                                          
               Iter. | Hartree-Fock Energy | Energy Change | Gradient Norm | Max. Gradient | Density Change               
               --------------------------------------------------------------------------------------------               
                  1       -74.820748697856    0.0000000000      0.00026411      0.00004348      0.00000000                
                  2       -74.820748745254   -0.0000000474      0.00008006      0.00002170      0.00039160                
                  3       -74.820748747305   -0.0000000021      0.00000755      0.00000219      0.00006846                
                  4       -74.820748747316   -0.0000000000      0.00000035      0.00000008      0.00000419                
                                                                                                                          
               *** SCF converged in 4 iterations. Time: 0.02 sec.                                                         
                                                                                                                          
               Spin-Restricted Hartree-Fock:                                                                              
               -----------------------------                                                                              
               Total Energy                       :      -74.8207487473 a.u.                                              
               Electronic Energy                  :      -82.3603220321 a.u.                                              
               Nuclear Repulsion Energy           :        7.5395732848 a.u.                                              
               ------------------------------------                                                                       
               Gradient Norm                      :        0.0000003470 a.u.                                              
                                                                                                                          
                                                                                                                          
               Ground State Information                                                                                   
               ------------------------                                                                                   
               Charge of Molecule            :  0.0                                                                       
               Multiplicity (2S+1)           :  1.0                                                                       
               Magnetic Quantum Number (M_S) :  0.0                                                                       
                                                                                                                          
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.26675 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21338 a.u.                                                                  
               (   1 O   1s  :     0.24) (   1 O   2s  :    -0.88) (   2 H   1s  :    -0.20)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53488 a.u.                                                                  
               (   1 O   2s  :    -0.42) (   1 O   1p-1:     0.60) (   1 O   1p0 :    -0.25)                              
               (   2 H   1s  :     0.50) (   3 H   1s  :    -0.25)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.39126 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.37376 a.u.                                                                  
               (   1 O   2s  :    -0.28) (   1 O   1p-1:     0.38) (   1 O   1p0 :     0.61)                              
               (   3 H   1s  :     0.58)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.27265 a.u.                                                                  
               (   1 O   2s  :    -0.33) (   1 O   1p-1:    -0.19) (   1 O   1p0 :    -0.71)                              
               (   2 H   1s  :     0.16) (   3 H   1s  :     0.82)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67914 a.u.                                                                  
               (   1 O   2s  :     0.60) (   1 O   1p-1:     0.82) (   1 O   1p0 :    -0.37)                              
               (   2 H   1s  :    -1.15)                                                                                  
                                                                                                                          

We can reuse the code we wrote in the Configuration Interaction section to compute the inactive Fock matrix, energy and the active 2-electron integrals:

nbas = vlx.MolecularBasis.get_dimensions_of_basis(basis, molecule)

V_nuc = molecule.nuclear_repulsion_energy()

# one-electron Hamiltonian
kinetic_drv = vlx.KineticEnergyIntegralsDriver()
T = kinetic_drv.compute(molecule, basis).to_numpy()

nucpot_drv = vlx.NuclearPotentialIntegralsDriver()
V = -nucpot_drv.compute(molecule, basis).to_numpy()

h = T + V 

# two-electron Hamiltonian
eri_drv = vlx.ElectronRepulsionIntegralsDriver()
g = np.zeros((nbas, nbas, nbas, nbas))
eri_drv.compute_in_mem(molecule, basis, g)

def CI_integrals(C, nIn, nAct, h,g):
    Cact = C[:, nIn:nIn+nAct] #Active MOs
    
    # Compute the inactive Fock matrix
    Din = np.einsum('ik,jk->ij', C[:, :nIn], C[:, :nIn]) #inactive density
    Jin = np.einsum('ijkl,kl->ij', g, Din)
    Kin = np.einsum('ilkj,kl->ij', g, Din)
    Fin = h + 2*Jin - Kin
    
    # Transform to MO basis
    Ftu = np.einsum("pq, qu, pt->tu", Fin, Cact, Cact)
    
    #Inactive energy:
    Ein = np.einsum('ij,ij->', h + Fin, Din) + V_nuc

    #Compute the MO 2-electron integrals
    pqrw = np.einsum("pqrs,sw->pqrw", g   , Cact)
    pqvw = np.einsum("pqrw,rv->pqvw", pqrw, Cact)
    puvw = np.einsum("pqvw,qu->puvw", pqvw, Cact) #This intermediate will also be used later
    tuvw = np.einsum("puvw,pt->tuvw", puvw, Cact)
    return Ein, Ftu, tuvw, Fin, puvw

Using this, we can implement the MCSCF iterations:

max_iter = 40
conv_thresh = 1e-4

space=mtp.OrbSpace(molecule, scfdrv.mol_orbs) #MolSpace will store the orbitals for us
space.CAS(2,2)

nIn = space.nOcc #Number of inactive orbitals
nAct = space.nAct #Number of active orbitals

silent = vlx.OutputStream(None) #Deactivate printing
CIdrv = mtp.CIDriver(ostream=silent)

print("iter    MCSCF energy    Error norm")

for iter in range(max_iter):
    C = space.mol_orbs.alpha_to_numpy()
    Cact = C[:, nIn:nIn+nAct] #Active MOs
    
    #Obtain the integrals needed for CI
    Ein, Ftu, tuvw, Fin, puvw = CI_integrals(C, nIn, nAct, h, g)
    
    #Feed them to the CI driver and compute the CI energy
    CIdrv.UpdateInts(Ein, Ftu, tuvw)
    CIdrv.compute(molecule, basis, space) #Compute only the ground state
    E = CIdrv.getEnergy(0)
    
    #Obtain CI densities
    Dact = CIdrv.get1den(0)
    D2act = CIdrv.get2den(0)
    
    #Active Fock matrix
    Dact_pq = np.einsum("tu,pt,qu->pq", Dact, Cact, Cact) #Transform to AO basis
    Jact = np.einsum('ijkl,kl->ij', g, Dact_pq)
    Kact = np.einsum('ilkj,kl->ij', g, Dact_pq)
    Fact = 2 * Jact - Kact
    
    #Form effective Fock matrix
    Feff = np.zeros((nbas,nbas))
    Feff[:nIn,:] = np.einsum("pq,pt,qn->tn", 2*Fin+Fact, C[:, :nIn], C) #Fiq
    Feff[nIn:nIn+nAct,:] = np.einsum("tu,pu,pq,qn->tn", Dact, Cact, Fin, C) #Ftq (1)
    Feff[nIn:nIn+nAct,:] += np.einsum("quvw,tuvw,qn->tn", puvw, D2act, C) #Ftq (2)
    
    #Form gradient 2(Fpq-Fqp)
    G = 2 * (Feff - np.transpose(Feff))
    
    #Check convergence
    e_vec = np.reshape(G, -1)
    error = np.linalg.norm(e_vec)
    print(f'{iter+1:>2d}  {E:16.8f}  {error:10.2e}')
    if error < conv_thresh:
        print('MCSCF iterations converged!')
        break
    
    #Extract some diagonals
    diag1 = np.einsum("pq,pm,qm->m", 2*Fin+Fact, C, C) #Diagonal of 2*Fin+Fact in MO basis
    diag2 = np.diagonal(Feff) #Diagonal of the effective Fock matrix
    
    #Form Hessian diagonal
    Hess = np.zeros((nbas,nbas))
    Hess[:nIn,nIn:] = 2* diag1[nIn:] - 2* diag1[:nIn].reshape(-1,1) #Sum of a line and column vectors
    Hess[nIn:nIn+nAct,:] = - 2 * diag2[nIn:nIn+nAct].reshape(-1, 1)
    Hess[nIn:nIn+nAct,nIn+nAct:] += np.einsum('tt,a->ta',Dact,diag1[nIn+nAct:])
    Hess[nIn:nIn+nAct,:nIn] += np.einsum('tt,a->ta',Dact,diag1[:nIn])
    Hess += np.transpose(Hess)
    Hess[:nIn,:nIn] = 1 #To avoid division by 0
    Hess[nIn + nAct:, nIn + nAct:] = 1 #To avoid division by 0
    
    #Finally, compute next step
    #X = np.zeros((nbas,nbas))
    X = G / Hess
    expX = scipy.linalg.expm(X)
    newmo = np.matmul(C,expX)
    
    ene = np.zeros(nbas)
    occ = np.zeros(nbas)
    newmolorb = vlx.MolecularOrbitals([newmo], [ene], [occ], vlx.molorb.rest)
    space.mol_orbs = newmolorb
iter    MCSCF energy    Error norm
 1      -74.88252747    2.25e-01
 2      -74.89753572    6.02e-02
 3      -74.89903251    2.29e-02
 4      -74.89930538    1.40e-02
 5      -74.89938498    9.82e-03
 6      -74.89941463    6.75e-03
 7      -74.89942666    4.54e-03
 8      -74.89943169    3.03e-03
 9      -74.89943383    2.01e-03
10      -74.89943474    1.33e-03
11      -74.89943514    8.84e-04
12      -74.89943531    5.86e-04
13      -74.89943538    3.89e-04
14      -74.89943542    2.58e-04
15      -74.89943543    1.71e-04
16      -74.89943544    1.14e-04
17      -74.89943544    7.55e-05
MCSCF iterations converged!
#Compare to the MCSCF driver of multipsi
space = mtp.OrbSpace(molecule, scfdrv.mol_orbs)
space.CAS(2,2)

Mcscfdrv = mtp.McscfDriver()
Mcscfdrv.compute(molecule, basis, space)
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 4
Number of active orbitals:              2
Number of virtual orbitals:             1

    This is a CASSCF wavefunction: CAS(2,2)

          CI expansion:
          -------------
Number of determinants:      3


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -74.882527473     0.0e+00      1.1e-01          1   0:00:00
        2     -74.897532702    -1.5e-02      3.2e-02          1   0:00:00
        3     -74.899246178    -1.7e-03      1.8e-02          1   0:00:00
        4     -74.899382126    -1.4e-04      7.5e-03          1   0:00:00
        5     -74.899429106    -4.7e-05      2.5e-03          1   0:00:00
        6     -74.899434654    -5.5e-06      1.2e-03          1   0:00:00
        7     -74.899435327    -6.7e-07      3.8e-04          1   0:00:00
        8     -74.899435422    -9.4e-08      2.1e-04          1   0:00:00
        9     -74.899435440    -1.9e-08      5.8e-05          1   0:00:00
       10     -74.899435442    -1.1e-09      1.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 10 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -74.89943544157018
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.79682 0.20318
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.27910 a.u.                                                                  
               (   1 O   1s  :     0.99)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.21811 a.u.                                                                  
               (   1 O   1s  :    -0.24) (   1 O   2s  :     0.89) (   2 H   1s  :     0.21)                              
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.53226 a.u.                                                                  
               (   1 O   2s  :     0.49) (   1 O   1p-1:    -0.68) (   2 H   1s  :    -0.50)                              
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -0.40293 a.u.                                                                  
               (   1 O   1p+1:    -1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.797 Energy:   -0.35223 a.u.                                                                  
               (   1 O   1p-1:     0.20) (   1 O   1p0 :     0.63) (   3 H   1s  :     0.64)                              
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.203 Energy:    0.24232 a.u.                                                                  
               (   1 O   2s  :    -0.25) (   1 O   1p0 :    -0.75) (   3 H   1s  :     0.82)                              
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.66509 a.u.                                                                  
               (   1 O   2s  :     0.63) (   1 O   1p-1:     0.83) (   1 O   1p0 :    -0.30)                              
               (   2 H   1s  :    -1.16)                                                                                  
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00

MultiPsi uses several tools to accelerate convergence, in particular a Hessian update to fix for the fact that we are using an approximate Hessian, but this is beyond the scope of this chapter.

Multireference correlation#

For any reasonable size molecule, the active space will be but a fraction of the total orbital space, and thus, MCSCF provides only a small (though important) fraction of the total correlation. We typically say, somewhat incorrectly, that MCSCF captures the static correlation but still lacks dynamical correlation.

However, the same way as MCSCF can be seen as an extension of Hartree-Fock to the multiconfigurational case, there exists extensions of standard correlation methods (MP2, truncated CI, coupled cluster and even DFT) to the multiconfigurational case. However, several complications arise when generalizing single reference correlation to the multiconfigurational case, and several multireference variants exist for each single reference correlation method.

One of the most important difficulty in wavefunction-based multireference correlation is the choice of the n-particle basis. Let’s look at CISD and its multireference (MR) equivalent MRCISD as an example, though the discussion is very similar for multireference perturbation theory and multireference coupled cluster.

In CISD, the correlated wavefunction is expanded on a basis of singly and doubly excited determinants. Those are generated by applying excitation operators to the reference (Hartree-Fock) wavefunction \(| 0 \rangle\) :

\[ | \Psi_{ijab} \rangle = \hat{a}^{\dagger}_b \hat{a}^{\dagger}_a\hat{a}_j\hat{a}_i | 0 \rangle \]

The number of such functions is \(N_\mathrm{O}^2 N_\mathrm{V}^2\) with \(N_\mathrm{O}\) and \(N_\mathrm{V}\) the number of occupied and virtual orbitals respectively. These functions form an orthonormal basis and are orthogonal to the reference function.

A MCSCF wavefunction is already a linear combination of Slater Determinant:

\[ | \Psi_{\text{MCSCF}} \rangle = \sum_I c_I | \mathbf{I} \rangle \]

We thus have 2 ways to generate our MRCISD functions. The first is to apply the excitation operators to each \(| \mathbf{I} \rangle\) function:

\[ | \Psi_{ijab\mathrm{I}} \rangle = \hat{a}^{\dagger}_b \hat{a}^{\dagger}_a\hat{a}_j\hat{a}_i | \mathbf{I} \rangle \]

Note that we only write the \(ijab\) excitation but the MRCISD basis also needs to include excitations to and from the active orbitals.

These \(| \Psi_{ijab\mathrm{I}} \rangle \) have the same desirable property of forming an orthonormal basis. However, there are many of them, on the order of \(N_\mathrm{O}^2 N_\mathrm{V}^2 N_{CI}\) with \(N_{CI}\) the (potentially very large) number of determinants in our MCSCF. Let’s see this number in the example of a water CAS(6,5):

h2o_xyz = """3
water                                                                                                                          
O    0.000000000000        0.000000000000        0.000000000000                         
H    0.000000000000        0.740848095288        0.582094932012                         
H    0.000000000000       -0.740848095288        0.582094932012
"""

molecule = vlx.Molecule.from_xyz_string(h2o_xyz)

basis = vlx.MolecularBasis.read(molecule, "6-31G")

scfdrv = vlx.ScfRestrictedDriver(ostream=vlx.OutputStream(None))
scfdrv.compute(molecule, basis)

space = mtp.OrbSpace(molecule,scfdrv.mol_orbs)
space.CISD()

expansion = mtp.CIExpansion(space)

print("Number of CISD Determinants  :", expansion.nDet)

space.CAS(6,5)

expansion = mtp.CIExpansion(space)
print("Number of MCSCF Determinants :", expansion.nDet)

space.MRCISD()

expansion = mtp.CIExpansion(space)

print("Number of MRCISD Determinants:", expansion.nDet)
Number of CISD Determinants  : 1141
Number of MCSCF Determinants : 55
Number of MRCISD Determinants: 31345

Even with this very small active space, the number of MRCISD determinants become significantly larger than a standard CISD.

Alternatively, we could write our MRCISD expansion in a similar way to the CISD, by applying the excitation operators directly to the entire MCSCF wavefunction

\[\begin{split} | \Psi_{ijab} \rangle & = \hat{a}^{\dagger}_b \hat{a}^{\dagger}_a\hat{a}_j\hat{a}_i | \Psi_{\text{MCSCF}} \rangle \\ & = \hat{a}^{\dagger}_b \hat{a}^{\dagger}_a\hat{a}_j\hat{a}_i (\sum_I c_I | \mathbf{I} \rangle) \end{split}\]

In Multireference theory, the excitations within the active space are called internal excitations, thus the formulation above where those excitations are fixed to the MCSCF converged result is called “internal contraction”.

The advantage of this formulation is rather obvious. The size of our basis is now on the order of that of a standard CISD (differing only by the inclusion of occupied to active and active to virtual excitations). However, those functions are now significantly harder to manipulate. Each function is not a Slater Determinant but a linear combination of them, and in particular, this means that those functions are not all orthonormal. To see this, let’s take the specific example of \(itua\) excitations, that is a double excitation with one electron excited from inactive to active and one from active to virtual. The overlap between 2 such excitations with the same \(i\) and \(a\) but different active orbitals is:

\[ \langle \Psi_{itua} | \Psi_{ivwa} \rangle = \langle \Psi_{\text{MCSCF}} | \hat{a}^{\dagger}_u \hat{a}_t \hat{a}^{\dagger}_w\hat{a}_v | \Psi_{\text{MCSCF}} \rangle \]

which is related to the active 2-body density matrix and is not in general 0.

These complications get even worse when computing Hamiltonian matrix elements between such determinants, and thus, straightforward implementation of MRCISD involves up to 5-particle density matrix in the active space.

Some tricks have been found to reduce this number, but those internally contracted methods remain definitely more complex to implement than the uncontracted ones. Also, the additional flexibility in uncontracted method makes them slightly more accurate. Still the superior performance of internally contracted methods when medium to large active spaces are used makes them very attractive for the user. Below is a summary of some of the main multireference methods in existence.

Single reference method

Uncontracted MR method

Internally contracted MR

MP2

MRMP2

CASPT2, NEVPT2

CISD

MRCISD

ic-MRCISD

CCSD

Mk-MRCCSD

ic-MRCCSD

MultiPsi currently only implements an uncontracted MRCISD. The workflow is to first compute a MCSCF and then add a MRCISD on top of it:

space.CAS(6,5)

mcscfdrv = mtp.McscfDriver()
mcscfdrv.compute(molecule,basis,space)

space.MRCISD() #Assumes a CAS has been defined before

cidrv = mtp.CIDriver()
cidrv.compute(molecule,basis,space)
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 2
Number of active orbitals:              5
Number of virtual orbitals:             6

    This is a CASSCF wavefunction: CAS(6,5)

          CI expansion:
          -------------
Number of determinants:      55


                                                                                                                          
        MCSCF Iterations
        ----------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm | CI Iter. |   Time
     ---------------------------------------------------------------------
        1     -75.989917004     0.0e+00      3.2e-02          1   0:00:00
        2     -76.003710349    -1.4e-02      6.0e-02          1   0:00:00
        3     -76.029254431    -2.6e-02      3.1e-02          1   0:00:00
        4     -76.033207654    -4.0e-03      3.6e-02          1   0:00:00
        5     -76.035329839    -2.1e-03      1.5e-02          1   0:00:00
        6     -76.035529698    -2.0e-04      7.1e-03          1   0:00:00
        7     -76.035635032    -1.1e-04      5.2e-03          1   0:00:00
        8     -76.035668304    -3.3e-05      3.4e-03          1   0:00:00
        9     -76.035672093    -3.8e-06      1.5e-03          1   0:00:00
       10     -76.035672867    -7.7e-07      4.2e-04          1   0:00:00
       11     -76.035672920    -5.3e-08      2.1e-04          1   0:00:00
       12     -76.035672930    -1.0e-08      7.5e-05          1   0:00:00
       13     -76.035672932    -1.7e-09      2.2e-05          1   0:00:00
                                                                                                                          
** Convergence reached in 13 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -76.03567293169105
- S^2   : -0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99934 1.97953 1.97649 0.02258 0.02206
                                                                                                                          
                                                 Spin Restricted Orbitals                                                 
                                                 ------------------------                                                 
                                                                                                                          
               Molecular Orbital No.   1:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:  -20.55178 a.u.                                                                  
               (   1 O   1s  :     1.00)                                                                                  
                                                                                                                          
               Molecular Orbital No.   2:                                                                                 
               --------------------------                                                                                 
               Occupation: 2.000 Energy:   -1.06888 a.u.                                                                  
               (   1 O   1s  :    -0.22) (   1 O   2s  :     0.48) (   1 O   3s  :     0.57)                              
               (   1 O   1p0 :    -0.24) (   1 O   2p0 :    -0.19)                                                        
                                                                                                                          
               Molecular Orbital No.   3:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.999 Energy:   -0.50342 a.u.                                                                  
               (   1 O   1p+1:     0.64) (   1 O   2p+1:     0.51)                                                        
                                                                                                                          
               Molecular Orbital No.   4:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.980 Energy:   -0.85571 a.u.                                                                  
               (   1 O   1p0 :     0.51) (   1 O   2p0 :     0.34) (   2 H   1s  :     0.21)                              
               (   3 H   1s  :     0.21)                                                                                  
                                                                                                                          
               Molecular Orbital No.   5:                                                                                 
               --------------------------                                                                                 
               Occupation: 1.976 Energy:   -0.71192 a.u.                                                                  
               (   1 O   1p-1:    -0.51) (   1 O   2p-1:    -0.25) (   2 H   1s  :    -0.27)                              
               (   3 H   1s  :     0.27)                                                                                  
                                                                                                                          
               Molecular Orbital No.   6:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.023 Energy:    0.78287 a.u.                                                                  
               (   1 O   1p-1:     0.88) (   2 H   1s  :    -0.47) (   2 H   2s  :    -0.29)                              
               (   3 H   1s  :     0.47) (   3 H   2s  :     0.29)                                                        
                                                                                                                          
               Molecular Orbital No.   7:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.022 Energy:    0.76609 a.u.                                                                  
               (   1 O   2s  :    -0.52) (   1 O   3s  :    -0.16) (   1 O   1p0 :    -0.78)                              
               (   1 O   2p0 :     0.19) (   2 H   1s  :     0.44) (   2 H   2s  :     0.19)                              
               (   3 H   1s  :     0.44) (   3 H   2s  :     0.19)                                                        
                                                                                                                          
               Molecular Orbital No.   8:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.67157 a.u.                                                                  
               (   1 O   2s  :     0.20) (   1 O   3s  :    -1.26) (   1 O   1p0 :     0.41)                              
               (   1 O   2p0 :    -0.77) (   2 H   1s  :    -0.38) (   2 H   2s  :     1.14)                              
               (   3 H   1s  :    -0.38) (   3 H   2s  :     1.14)                                                        
                                                                                                                          
               Molecular Orbital No.   9:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    0.78151 a.u.                                                                  
               (   1 O   1p-1:     0.28) (   1 O   2p-1:    -0.73) (   2 H   1s  :    -0.61)                              
               (   2 H   2s  :     1.63) (   3 H   1s  :     0.61) (   3 H   2s  :    -1.63)                              
                                                                                                                          
               Molecular Orbital No.  10:                                                                                 
               --------------------------                                                                                 
               Occupation: 0.000 Energy:    1.16341 a.u.                                                                  
               (   1 O   1p+1:    -0.96) (   1 O   2p+1:     1.04)                                                        
                                                                                                                          
                                                                                                                          
Total MCSCF time: 00:00:00
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              13
Number of virtual orbitals:             0

    This is a GASSCF wavefunction
           
         Cumulated   Min cumulated    Max cumulated 
 Space    orbitals      occupation       occupation
     1           2               2                4
     2           7               8               10
     3          13              10               10


          CI expansion:
          -------------
Number of determinants:      31345


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -76.060395166     0.0e+00      2.2e-01   0:00:00
        2     -76.114414378    -5.4e-02      1.1e-02   0:00:00
        3     -76.117082173    -2.7e-03      7.9e-04   0:00:00
        4     -76.117270862    -1.9e-04      7.1e-05   0:00:00
        5     -76.117287006    -1.6e-05      7.1e-06   0:00:00
        6     -76.117288911    -1.9e-06      1.1e-06   0:00:00
        7     -76.117289237    -3.3e-07      1.5e-07   0:00:00
        8     -76.117289276    -3.9e-08      1.7e-08   0:00:00
        9     -76.117289280    -4.5e-09      2.3e-09   0:00:00
                                                                                                                          
** Convergence reached in 9 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -76.11728928021503
- S^2   : -0.01  (multiplicity = 1.0 )
- Natural orbitals
1.99996 1.98889 1.98179 1.97324 1.96991 0.02673 0.02502 0.01705 0.01146 0.00290 0.00205 0.00055 0.00042

Note that MCSCF wavefunction satisfies the extended Brillouin theorem, which is a generalization of the Brillouin theorem of Hartree-Fock saying that the MCSCF wavefunction does not interact with single excitations. Because of this, internally contracted MRCIS does not improve upon the ground state MCSCF energy, in the same way as CIS does not improve upon HF. However, uncontracted MRCIS does bring some correlation as it allows a single excitation outside the active space to correlate with internal excitations.

space.CAS(6,5)
space.MRCIS()

cidrv = mtp.CIDriver()
cidrv.compute(molecule,basis,space)
          Active space definition:
          ------------------------
Number of inactive (occupied) orbitals: 0
Number of active orbitals:              13
Number of virtual orbitals:             0

    This is a GASSCF wavefunction
           
         Cumulated   Min cumulated    Max cumulated 
 Space    orbitals      occupation       occupation
     1           2               3                4
     2           7               9               10
     3          13              10               10


          CI expansion:
          -------------
Number of determinants:      2555


                                                                                                                          
        CI Iterations
        -------------
                                                                                                                          
     Iter. | Average Energy | E. Change | Grad. Norm |   Time
     ----------------------------------------------------------
        1     -76.061845506     0.0e+00      6.9e-02   0:00:00
        2     -76.080097580    -1.8e-02      1.8e-03   0:00:00
        3     -76.080624764    -5.3e-04      7.4e-05   0:00:00
        4     -76.080644363    -2.0e-05      4.3e-06   0:00:00
        5     -76.080645670    -1.3e-06      3.4e-07   0:00:00
        6     -76.080645770    -1.0e-07      2.5e-08   0:00:00
        7     -76.080645777    -7.1e-09      2.5e-09   0:00:00
                                                                                                                          
** Convergence reached in 7 iterations
                                                                                                                          
        Final results
        -------------
                                                                                                                          
* State 1
- Energy: -76.08064577744042
- S^2   : 0.00  (multiplicity = 1.0 )
- Natural orbitals
1.99999 1.99559 1.99011 1.97597 1.97190 0.02634 0.02516 0.00879 0.00451 0.00081 0.00069 0.00011 0.00003
print("Uncontracted MRCIS dynamical correlation:", cidrv.getEnergy(0)-mcscfdrv.getEnergy(0))
Uncontracted MRCIS dynamical correlation: -0.04497284574939897