Localized Atomic and Molecular Orbitals. II

Abstract

Using a recently proposed procedure, the localized molecular orbitals are determined for minimal-basis-set LCAO—SCF wavefunctions of the molecules LiH, BH, NH, FH, Li2, B2, Be2, N2, F2, CO, BF, LiF. In all cases, well-defined inner-shell, lone-pair, and bond orbitals are found. They exhibit a considerable degree of transferability between different molecules, and the s-p hybridization varies regularly across the periodic table. In some cases the localized molecular orbitals deviate from accepted intuition; in all cases the exact determination of intrasymmetry localization is important. A close relation is found between the localized molecular orbitals and those molecular orbitals which extremize the MO-overlap populations. In the case of the HF molecule, the localized orbitals are also determined for the exact self-consistent-field wavefunction and, the transformation from canonical to localized molecular orbitals is found to be almost identical with that in the minimal-basis-set approximation. Implications of the localization procedures and its results are discussed.