π-bonded model of an oxygen-vacancy center in SiO

Tight-binding total energy calculations of the two possible states of the neutral oxygen-vacancy center in SiO have been performed within the bond orbital approximation. It has been shown that the lowest energy state is realized by a transfer of one electron from a nonbonding p oxygen orbital (next to the vacancy) into an opposite silicon dangling hybrid, and then by the formation of a π bond between the remaining oxygen p electron and the nearest silicon dangling hybrid. The new π-bonded model of the oxygen-vacancy center is discussed and the results obtained are compared with experimental data. The most important aspect of this work is the demonstration that for defects in SiO, the π interactions are very important and should not be neglected in describing the physics of many problems in SiO.