Multicenter Integrals in Quantum Mechanics. II. Evaluation of Electron-Repulsion Integrals for Slater-Type Orbitals

Abstract

A unified method for the evaluation of electron‐repulsion integrals for Slater‐type orbitals is described. This method applies to every electron‐repulsion integral needed for polyatomic molecule calculations, and is sufficiently general to handle integrals over orbitals with higher quantum numbers, located at arbitrary spatial points with arbitrary relative orientations. Computation programs have been prepared to implement this analysis with emphasis on both the requirements of speed and accuracy in evaluating the large number of electron‐repulsion integrals required for a polyatomic calculation. Comparisons with other methods are given which indicate that this unified approach can result in at least an order‐of‐magnitude saving in computation time for large molecular systems.