AB INITIO STUDIES OF ORBITAL HYBRIDIZATION IN POLYATOMIC MOLECULES

Single-determinant molecular orbital wavefunctions are constructed for a variety of polyatomic molecules using well-known techniques of hybridization and bond orbital formation. Such concepts generally are employed for qualitative purposes; however, in the present study the emphasis is on a quantitative comparison of energies and wavefunctions with results of ab initia SCF treatments. All electrons are included in the formulation, and all integrals over basis functions are evaluated accurately in order to permit rigorous use of the variational theorem. Minimization of the total energy of a molecule with respect to hybrid angles and bond polarity parameters is found to give energies and wavefunctions in rather good agreement with the minimal LC (Hartree-Fock) AO SCF limit for the systems investigated. Hybridization and bond polarity parameters are reported for a number of systems, and these results provide an assessment of the validity of certain widely used qualitative concepts. The applicability of the procedure in predicting useful molecular wavefunctions and SCF starting vectors is discussed.