| Abstract
| - We have performed systematic ab initio calculations to study the structures and stability of Si6On clusters(n = 1−12) in order to understand the oxidation process in silicon systems. Our calculation results show thatoxidation pattern of the small silicon cluster, with continuous addition of O atoms, extends from one side tothe entire Si cluster. Si atoms are found to be separated from the pure Si cluster one-by-one by insertion ofoxygen into the Si−O bonds. From fragmentation energy analyses, it is found that the Si-rich clusters usuallydissociate into a smaller pure Si clusters (Si5, Si4, Si3, or Si2), plus oxide fragments such as SiO, Si2O2, Si3O3,Si3O4, and Si4O5. We have also studied the structures of the ionic Si6On± (n = 1−12) clusters and found thatmost of ionic clusters have different lowest-energy structures in comparison with the neutral clusters. Ourcalculation results suggest that transformation Si6On+(a) + O → Si6On+1+(a) should be easier.
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