Molecular integrals in the generalized hylleraas–CI method

Abstract

In the generalized Hylleraas-cr method, the original correlation factor r ; is multiplied by a Gaussian gerninal. Using the approach of generating functions, the general formulas of molecular integrals in this method are derived over Cartesian Gaussian orbitals. From differentiations of the generating functions, the expanding length in the incomplete Gamma functions is reduced, and some cancellations presented in other approaches are avoided. Preliminary calculations for H2 and H2-H, systems are carried out over STO-3G basis. The results are encouraging.

Shorter Expansions of Molecular Integrals in Hylleraas-CI Calculations

“…In order to remove systematically the terms that would exactly cancel one another, we follow the same technique used in Ref. [10]. At first, elaborate cancelations are completed in the case of a-type functions.…”