Evaluation of two-center overlap and coulomb integrals derived from slater-type orbitals

The strategy for the evaluation of two-center overlap and Coulomb integrals is illustrated by using computer-generated formulas produced from 1s orbitals. There is no loss in generality as these formulas have the same structure for higher quantum numbers. For small parameter values, singularities may be removed from the formulas by expanding exponential functions and collecting coefficients of like powers by machine. Suitable terminated expansions, along with exact formulas, permit high accuracy throughout the entire possible range of parameter values.