A SIMPLIFIED MODEL OF OLIGOSILANE IONIZATION ENERGIES

Ab initio electron propagator calculations with effective core potentials on Si and a double zeta basis produce accurate vertical ionization energies and Feynman-Dyson amplitudes (FDA's) for oligosilanes. The calculations determine variations in ionization energies and ground state total energies with respect to bond angle and dihedral angle distortions and obtain excellent agreement with photoelectron spectra and with previous all-electron calculations with larger basis sets. Second order, diagonal self energies contain the bulk of the relaxation and correlation effects. FDA's accompanying the ionization energies are built from Si-Si bond functions. Phase relationships between neighboring bond functions determine how bond angles affect the ionization energies of Si3H8. The variation of ionization energies with respect to dihedral angles in the Si backbones of Si4H10 and Si5H12 depends on phase relationships between first non-neighbor bond functions.