Second row molecular orbital calculations. Minimal and minimal + 3d basis calculations on second row diatomics

Abstract

The optimal valence orbital exponents of a series of 24 diatomic molecules containing second row atoms are determined, with and without 3d orbitals in the basis set. Equilibrium bond lengths and dipole moments are calculated using Slater exponents as well as the optimal values. It is found that optimization of valence s and p exponents is as important as the addition of d orbitals to the basis set for bond length predictions and that separate optimization of d exponents does not significantly improve calculated bond lengths. The computed dipole moments are less satisfactory for all basis sets, although the optimal exponent basis including d orbitals are in best overall agreement with experiment.