Energy Derivatives of Correlated Wavefunctions: A Matrix Directed Approach (Dimagnesium)

The appropriate expressions for obtaining the first derivative of the correlated Self-Consistent Electron Pair (SCEP) wavefunction are presented. The matrix directed, pair operator approach used within the SCEP formalism allows certain redundancies found in ordinary configurational-type correlated derivative calculations to be eliminated. Calculation of the first order changes in the molecular orbital coefficients via a Coupled Perturbed Hartree Fock procedure is essential in this formulation as in all other derivative CI techniques. Determination of these coefficients provides a means by which a transformation between the usual pair coefficient matrices of SCEP and their derivative counterparts may be effected. Since many of the matrix operators necessary in the derivative evaluation are necessarily constructed and stored in the energy evaluation, calculational time is minimized. Demonstration calculations using this method are performed for electric field derivatives. Results comparing expectation values versus analytic derivative values are presented for HF and CO as a function of basis set and internuclear distance.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Jasien, Paul Gerard

• Chemistry, Physical

Identifier

(UMI)AAI8502191

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/70277