Scine::Sparrow  5.0.0
Library for fast and agile quantum chemical calculations with semiempirical methods.
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CISTestSigmaVectorEvaluator Class Reference

This class evaluates the -vectors for the Davidson-Liu algorithm for both reference calculations (J. B. Foresman, M. Head-Gordon, J. A. Pople and M. J. Frisch; J. Phys. Chem. 1992, 96, 1, 135-149.) More...

#include <CISSigmaVectorEvaluator.h>

Collaboration diagram for CISTestSigmaVectorEvaluator:
Collaboration graph

Detailed Description

This class evaluates the -vectors for the Davidson-Liu algorithm for both reference calculations (J. B. Foresman, M. Head-Gordon, J. A. Pople and M. J. Frisch; J. Phys. Chem. 1992, 96, 1, 135-149.)

This class is especially designed for the calculation of the sigma vectors in a pruned singly excited determinant space. After the preceding calculation of the two-electron integrals in atomic orbital basis by the CISAOFockBuilder, the calculation of the pseudo-Fock matrix in atomic orbital basis with the pseudo-densities from the CISPseudoDensityBuilder and the energy-difference vector (TimeDependentUtils), the sigma-vectors can be calculated like this

for a restricted reference (S for singlet excitation, T for triplet excitation):

^S_{(ia)} = b_(ia) * (e_a - e_i) + C^t ~ F^S_{ia}~ C ^T_{(ia)} = b_(ia) * (e_a - e_i) + F^T_{ia}

and for an unrestricted reference ( and respectively)

{(ia)} = b_(ia) * (e_a - e_i) + F_{ia}

\(b\): guess vector

\(e\): energy level

\(F\): pseudo-Fock matrix

The documentation for this class was generated from the following file: