New translation method for STOs and its application to calculation of two-center two-electron integrals

The new translation method for Slater-type orbitals (STOs) previously teste d in the case of the overlap integral is extended to the calculation of two -center two-electron molecular integrals. The method is based on the exact translation of the regular solid harmonic part of the orbital followed by t he series expansion of the residual spherical part in powers of the radial variable. Fair uniform convergence and stability under wide changes in mole cular parameters are obtained for all studied two-center hybrid, Coulomb, a nd exchange repulsion integrals. Ten-digit accuracy in the final numerical results is achieved through multiple precision arithmetic calculation of co mmon angular coefficients and Gaussian numerical integration of some of the analytical formulas resulting for the radial integrals. (C) 2000 John Wile y & Sons, Inc.