A TENSOR APPROACH TO 2-ELECTRON MATRIX-ELEMENTS

We present a new algorithm, the COLD PRISM, for computing matrix eleme nts in molecular orbital calculations. Whereas traditional approaches form these from two-electron repulsion integrals (ERIs) which, in turn , are formed from shell-pair data, we introduce several alternative pa ths that do not involve ERIs as intermediates. Tensor multiplication c an be used as the basic arithmetic operation on all of the new PRISM p aths and the associativity of tensor multiplication plays a key role. We have implemented our approach in the Q-Chem program. (C) 1997 Ameri can Institute of Physics.