Fragmentation of small silicon clusters.

Small silicon clusters have been the focus of several recent experimental studies using a variety of techniques. In particular, several groups have now investigated the fragmentation behavior of size-selected silicon cluster ions. However, there has not been any theoretical study where detailed comparison with the experimental fragmentation channels has been attempted. In this work, we have performed accurate ab initio quantum chemical calculations to study the structures and energies of small silicon clusters (Si sub n, n=2-10). The effects of polarization functions and electron correlation have been included in these calculations. The ground state binding energies of the clusters have been used to interpret the results of recent photofragmentation experiments on the ionic silicon clusters up to Si sup + above sub 20. Fragmentation predominantly yields daughter ions which are energetically most stable, consistent with a unimolecular dissociation mechanism involving vibrationally excited clusters on the ground electronic potential surface.