CALCULATION OF MULTICENTER ELECTRON REPULSION INTEGRALS IN SLATER-TYPE BASIS-SETS USING THE SIGMA-SEPARATION METHOD

The application of the Sigma-separation method to the calculation of m ulticenter two-electron molecular integrals with Slater-type basis fun ctions is reported. The approach is based on the approximation of a sc alar component of the two-center atomic density by a two-center expans ion over Slater-type functions. A least-squares fit was used to determ ine the coefficients of the expansion. The angular multipliers of the atomic density were treated exactly. It is shown that this approach ca n serve as a sufficiently accurate and fast algorithm for the calculat ion of multicenter two-electron molecular integrals with Slater-type b asis functions. (C) 1995 John Wiley and Sons, Inc.