COMPUTATION OF SOME NEW 2-ELECTRON GAUSSIAN INTEGRALS

The evaluation of a new form of two-electron integrals is required if the interelectronic distance r12 is used as a variable in the n-electron functions of electron correlation methods. The McMurchie-Davidson algorithm for the generation of molecular integrals over Gaussian-type functions is ideally suited to this. The new Gaussian integrals are formed from Hermite integrals over r12 (rather than l/r12) by standard techniques. The Hermite integrals over r12 itself are generated by a simple procedure with negligible computational effort. The key results are discussed in the context of general recursion formulas.