A quantum-mechanics/molecular-mechanics scheme was used to simulate the migration of charged defects in α-quartz. A quantum/molecular framework, together with a self-interaction correction scheme, was used to investigate the stability of the charged dimer defect and the E1’ center in α-quartz. The use of a self-interaction correction scheme made the charged dimer center unstable in α-quartz, in agreement with experimental failurs to identify this defect, while the effects of the correction of the self-interaction error on the E1’ center were negligible. It was suggested that, by overcoming a low-energy barrier, the puckering mechanism (ideally heading from the charged dimer defect to the E1’ center in self-interaction correction-free calculations) could be reiterated; allowing the drift of the positive charge localized on an over-coordinated O atom. This process could be regarded as an important channel of structural reorganization of O deficient silica in the presence of strong polarizing electric fields.

Migration of Positively Charged Defects in α-Quartz. T.Laino, D.Donadio, I.F.W.Kuo: Physical Review B, 2007, 76[19], 195210 (9pp)