An ab initio molecular dynamics study was made of the interconversion between O deficient centers (Si-Si bond, di-coordinated Si=Si:, and E’ centers) induced by UV irradiation of a-SiO2. By dynamical simulations in the excited state of a periodic model of a-SiO2, the reaction path and activation barrier for the Si-Si → =Si: interconversion was identified. A new competitive transformation of the excited, neutral Si-Si bond into two E’ centers was identified.

Ab Initio Simulations of Photo-Induced Interconversions of Oxygen Deficient Centers in Amorphous Silica. D.Donadio, M.Bernasconi, M.Boero: Physical Review Letters, 2001, 87[19], 195504 (4pp)