PHOTOELECTRON-SPECTRA AND MOLECULAR-PROPERTIES .81. VALENCE AND CORE IONIZATION ENERGIES FOR SIH4, H3SICL AND H3CCL FROM SCF AND PNO-CEPA CALCULATIONS

Valence and core ionization energies for the molecules SiH4, H3SiCl and H3CCl have been obtained from RHF-SCF and PNO-CEPA wavefunctions. The calculated vertical ionization energies IEnv(n = 1, 2, 3) agree within about 0.2 eV with the PE spectroscopically determined values for SiH4, H3SiCl and H3CCl. The increase in IE1v for H3SiCl relative to H3CCl, which has been previously ascribed to a different d-orbital participation in the two molecules, is already reproduced by calculations with (s, p) basis sets. The ΔSCF method has been used to predict several core ionization energies. In addition, relative intensities calculated for the ionizations into the 2A1 states of SiH46 are compared with available experimental data, and some spectroscopic constants for SiH4 and its ionic states are predicted. © 1979.