qrunch.chemistry.molecular_orbital_calculators

Module containing classes for calculating molecular orbitals.

The calculators are divided into mean field calculators and electron correlation calculators.

Classes

MolecularOrbitalCalculatorSubCreator

Molecular orbital calculator creator.

class MolecularOrbitalCalculatorSubCreator

Bases: MeanFieldCalculatorSubCreator[T]

Molecular orbital calculator creator.

__init__(parent: T, field_name: str) → None

Initialize a molecular orbital calculator creator.

Parameters:

parent (T) – Parent object to which the molecular orbital calculator will be assigned.
field_name (str) – Name of the field in the parent object where the molecular orbital calculator will be assigned.

Return type:

None

ccsd(options: CCSDCalculatorOptions | None = None) → T

Set the molecular orbital calculator to a coupled cluster singles and doubles (CCSD) calculator.

Uses a Hartree-Fock solution as a starting point, runs CCSD, then computes natural orbitals from the CCSD one-particle reduced density matrix. CCSD natural orbitals provide an improved description of electron correlation compared to MP2 natural orbitals.

Parameters:: options (CCSDCalculatorOptions | None) – Options for the CCSD calculator.
Return type:: T

dft(options: DftCalculatorOptions | None = None) → T

Set the mean-field calculator to a Kohn-Shahm DFT calculator, which is based on the PySCF implementation.

Parameters:: options (DftCalculatorOptions | None) – DFT calculator options.
Return type:: T

hartree_fock(options: HartreeFockCalculatorOptions | None = None) → T

Set the mean-field calculator to a Hartree-Fock calculator, which is based on the PySCF implementation.

Parameters:: options (HartreeFockCalculatorOptions | None) – Hartree-Fock calculator options.
Return type:: T

moller_plesset_2(options: MollerPlesset2CalculatorOptions | None = None) → T

Set the molecular orbital calculator to a Moller-Plesset 2nd order perturbation theory calculator.

The perturbation theory uses a Hartree-Fock solution as a starting point and applies second-order perturbative corrections to account for electron correlation effects. The resulting molecular orbitals are the so-called MP2 natural orbitals, which can provide a more accurate description of the electronic structure compared to the Hartree-Fock orbitals alone.

Parameters:: options (MollerPlesset2CalculatorOptions | None) – options for the Møller-Plesset calculator.
Return type:: T

Modules

`electron_correlation`	Module containing MP2 and CCSD molecular orbital solvers.
`mean_field`	Module containing PyScf solvers employing mean-field methods.
`molecular_orbital_calculators_protocols`	Contains the molecular orbital calculators.