Uniform Localization of Atomic and Molecular Orbitals. II

Uniformly localized molecular orbitals (LMO's) have been obtained from one-determinant wavefunctions of minimal-basis-set LCAO-SCF-MO's for CH4, NH3, H2O, H2CO, HCN, C2H6, C2H4, C2H2, and B2H6. The localization criterion is based on the simultaneous maximization in all the available (doubly filled) orbitals of local electron populations which are required be to localized around atoms or between pairs (sometimes triplets) of atoms in the molecule. The well-defined inner shell, lone pair, and localized bond orbitals resulting for polyatomic molecules appear to fit well into the usual concepts of conventional chemistry. As in the case of diatomics discussed in a previous publication, the uniformly localized orbitals obtained in the present paper prove to be very close to the corresponding LMO's resulting from the rather cumbersome method of maximizing the sum of the orbital self-repulsion energies.