In this section we will cover general aspects of electronic structure theory calculations.
Orbitals and basis sets
An introduction to wave functions for single-electron systems is given.
Many-electron wave functions
An introduction to many-electron wave functions is given.
Operators and matrix elements
An introduction to one- and two-electron operators is given together with a presentation of their associated matrix elements.
Reduced particle densities
One- and two-particle reduced densities are presented and illustrated.
Natural orbitals for restricted and unrestricted calculations are introduced.
A presentation of a technique to transform integrals in the AO basis to the MO basis as needed for correlated wave function methods.
Definitions of spin operators and a visual illustration of collinear and noncollinear spin densities.
Definition of correlation energy and a visual exploration of the effects of electron correlation on one- and two-particle densities.
Definition of interaction energy and visual illustration of its association with electron correlation. Dispersion correction by means of \(C_6\) coefficients is demonstrated.
Rayleigh–Schrödinger perturbation theory
A presentation of the perturbation theory in a form useful for Møller–Plesset methods.
A presentation of the occupation number formalism is given.
A presentation of group theory its application in chemistry is given.