(Received: July 12, 2005; Accepted for publication: November 24, 2005; Published on Web: December 15, 2005)
First, we review the general recursive expressions of molecular integrals overcontracted Gaussian functions which were reported by Honda, Yamaki, and Obara. Next, we have proposed an efficient algorithm for computing the electron repulsion integrals, and presented it in detail for the evaluationof <ppss> integrals. The present method has accomplished from 1.5 to 2.0 times faster computation than by GAMESS which is a widely used quantum-mechanical calculation program. The present algorithm is applicable to various kinds of molecular integrals, thus it would be very useful for further expansion of theoretical chemistry study.
Keywords: Molecular integral, General recursive expression, Contracted Gaussian, Hypergaussian
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