Ab initio MO studies of Si4NO+ clusters

The isomers of Si4NO+ cluster have been examined with ab initio MO calculations. The structures were determined at the MP2/6-31G∗ level of approximation, and their stability was verified by evaluating the harmonic frequencies. The most stable isomer of Si4NO+ is a complex of a Si3N+ ring and SiO, the structure of which is indicative of the eventual dissociation products, Si3N+ + SiO. This is consistent with the experimental result of the Sin+ + NO reaction leading to Sin − 1N+ + SiO fragments. A set of NO weakly adsorbed isomers was also located and verified to be easily yielded from Si4+ + NO reaction.