Local density calcuations on silicon-containing molecules. I. Silyl Chlorides

discrete-variation-method Hartree-Fock-Slater are reported for silane and for all four chlorosilanes at the experimental geometry. Self-consistency in the molecular studies was achieved using a self-consisten-charge method based on gross Mulliken populations, while the atomic bases set (a numerical HFS one) could also be reoptimized, using atomic configurations based on the molecular Mulliken populatios. We report data for ionization potentials and Mulliken populations, and some bonding information. The Si 3d functions play a negligible role for SiH₄, but their relative importance increases as the number of electronegative ligand species increases. The reasons for this originally suggested by Craig et al. and by Coulson are well borne out in the present study: the electronegative ligand species produces a partial positive charge on the Si due to σ-transfer, which draws in the d's on the Si, permitting dπ-pπ conjugation. Calculated results for ionization potentials are in good agreement with experiment, and reflect the increasing role of the d's both with state energy and with polarity.