Electronic structures and photoelectron spectra of Si-3 and Si-4

Vibrationally resolved photoelectron spectra of Si-3 and Si-4, recently reported by Kitsopoulos, Chick, Weaver, and Neumark, are interpreted using ab initio quantum chemical calculations of the ground and excited electronic states of the corresponding neutral clusters. The calculated electron affinities as well as the low-lying excitation energies agree within 0.1--0.2 eV of the experimental values, thus confirming the theoretically predicted structures of neutral and anionic Si3 and Si4 reported previously