Evaluation of Multicenter Integrals by Polished Brute-Force Techniques. II. Accuracy, Timing, Integral Values, and General Computational Considerations

Abstract

The analysis presented recently by the authors for the general evaluation of the multicenter electron-repulsion integrals 〈χa(1)χb*(1)(1 / r12)χc(2)χd*(2)〉 and the nuclear attraction integrals 〈χa(1)(1 / rc)χb*(1)〉 is briefly reviewed followed by a characterization of the method's accuracy, speed, and generality. Our method, which integrates a one-electron potential Vab with a one-electron charge distribution Ωcd, is operative on an IBM 360/75 computer for Slater-type orbitals with quantum numbers n ≤ 8,l ≤ n − 1,|m| ≤ l, arbitrary geometry, and scale factors. A precision of 10−6 hartree is routinely achieved at an average time per integral of between 100 and 200 msec depending upon the total number of integrals evaluated.