ABINITIO SCF CALCULATIONS ON [V10O28]6- - A BENCHMARK FOR THE CLASSICAL CALCULATION AND PROCESSING OF MOLECULAR INTEGRALS ON LARGE GAUSSIAN-BASIS SETS

A vector efficient implementation of the McMurchie and Davidson algorithm for the calculation of one- and two-electron molecular integrals is presented, as available in the Cray version of the ASTERIX program system. The implementation and performance of a vector-oriented strategy for the generation and processing of the P supermatrix is also discussed. This program system has been applied to the ab initio SCF computation of the ground-state wave function for the [V10O28]6- ion, with a basis set of triple-zeta quality for the valence shell of oxygen generating 1404 GTOs and 574 CGTOs for the complete system. The performance and the bottlenecks of the integral calculation are discussed as a function of the integral classes. Two-dimensional maps of the electrostatic potential are presented for this molecule and compared to experimental information about proton fixation.