Density-functional theory, and the nudged elastic-band method, were used to calculate migration pathways and to estimate the activation energy for the diffusion of O vacancies in α-quartz. Whereas the energy barrier for the diffusion of a neutral vacancy was very high (4.1eV), the binding of a triplet-state exciton to the vacancy decreased the barrier to 1.7eV. The attachment of a hole lowered the barrier to 1.9eV; thus making the vacancy mobile at normal annealing temperatures.

Migration of O Vacancies in α-Quartz - the Effect of Excitons and Electron Holes. J.Song, L.R.Corrales, G.Kresse, H.Jónsson: Physical Review B, 2001, 64[13], 134102