Benchmark values for two-center Coulomb integrals over slater-type orbitals

The Löwdin α‐function method, in which displaced orbitals are expanded in an infinite series of spherical harmonics, is implemented for Slater‐type orbitals using a commercial computer algebra program, Mathematica, The program, which is included, generates a C matrix with integer elements that characterizes our approach to multicenter molecular integrals. The general two‐center, two‐electron Coulomb repulsion integral is produced analytically with a finite number of terms. Each Coulomb formula may be evaluated to arbitrary precision, since Mathematica works with integer arithmetic. Hence, cancellation errors can be overcome. © 1993 John Wiley & Sons, Inc.