Complex electron affinity processes and ionization in the clusters Si3–Si10

Abstract

Vertical and adiabatic electron affinities and vertical ionization energies are presented for the clusters Sin, n=3,10 obtained from ab initio calculations with large basis sets. Electron correlation effects are taken into account by configuration interaction (CI) and Green function techniques. The clusters exhibit a complex behavior upon electron attachment. For each cluster there are several affinity states which result from capture of an electron into different orbitals. In some cases shake-up affinities are calculated which are positive. Si3 C2v is found to have at least three, Si4 D2h four, Si5 D3h two, Si5 C4v one, Si6 C2v three, Si7 D5h two, Si8 C2h five, Si9 Cs four, and Si10 C3v two affinity states (vertical processes, Sin+e−→Sin−+hν). The effects of electron correlation on the electron affinities are very large. In several cases the differences between the adiabatic and vertical electron affinities are exceedingly large amounting up to 1.5 eV.