A first-principles study of oxidation pattern in magic Si7 cluster

Oxidation pattern of the magic cluster Si7 was studied by first-principles calculations of Si7On (n = 1–14) clusters. The lowest-energy structures of the Si-rich clusters consist of a pure Si fragment and an oxide fragment. The oxidation is found to extend from one edge throughout the whole cluster as the number of the oxygen atoms increases. Fragmentation energy analysis shows that the Si-rich clusters can often dissociate into a small pure Sin (n = 2–6) cluster and a silicon oxide fragment. The O-rich clusters tend to separate into a SiO molecule and a silicon oxide fragment, except for Si7O14 which can easily lose an oxygen molecule in the fragmentation. The ionic clusters Si 7 O n ± (n = 1–14) were also studied.