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ACE algorithm for the rapid evaluation of the electron-repulsion integral over Gaussian-type orbitals

1996; Wiley; Volume: 59; Issue: 3 Linguagem: Inglês

10.1002/(sici)1097-461x(1996)59

1097-461X

Kazuhiro Ishida,

Atomic and Molecular Physics

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 (ps|ps) and (pp|pp) 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. © 1996 John Wiley & Sons, Inc.