Self-consistent molecular Hartree-Fock-Slater calculations - I. The computational procedure

A numerical-variational computational scheme for performing self-consistent molecular MO LCAO calculations in the HFS model is presented. The local exchange approximation is used. but the usual muffin-tin approximation for potentials or densities is avoided. Procedures specifically optimized for treating large systems, such as transition-metal complexes, are developed. Some illustrative results are given for small molecules. We show that one-electron energies can be calculated rapidly and that the charge distribution is also easily obtained. Total energies, and therefore optimized molecular geometries, require more computation time.