2-CENTER EXCHANGE INTEGRALS BETWEEN SLATER-TYPE ATOMIC ORBITALS

A novel general formula is developed which expresses two-center charge distributions over Slater-type atomic orbitals as expansions over terms of the form (ζ-1)k(ζ2-1)M/2ex(- αζ)'ylm(η, φ), where (ζ, η, φ) are elliptic coordinates. The formula is applied to derive compact expressions for the calculation of two-center exchange integrals arising from large basis sets. The program structure is discussed and computing times are quoted for these type integrals.