ACE ALGORITHM FOR THE RAPID EVALUATION OF THE ELECTRON-REPULSION INTEGRAL OVER GAUSSIAN-TYPE ORBITALS

摘要

A new series of general formulas to evaluate the electron-repulsion integral (ERI) can be derived from modifying the Gauss-Rys quadrature formula. These named as ''accompanying coordinate expansion (ACE) formulas'' are capable of evaluating very fast ERIs, especially for contracted Gaussian-type orbitals (GTOs). According to the degree of the contraction of GTOs, the optimum formula can be selected among these ACEs. Numerical examples are shown for(psps) and(pppp) ERIs as typical examples. It is found that the present ACE algorithm is numerically stable and is most efficient among all algorithms in the literature in the floating-point-operation (FLOP) count for all varieties of the degree of contraction. (C) 1996 John Wiley & Sons, Inc. [References: 18]