Charged Oxygen Defects in SiO2: Going beyond Local and Semilocal Approximations to Density Functional Theory

The long-standing problem of the oxygen self-diffusion mechanism in silicon dioxide, a prototypical oxide, both in the crystalline and in the amorphous phase, is studied from first principles. We demonstrate that the widely used local-density approximation to density functional theory (DFT) predicts a kinetic behavior of oxygen in strong disagreement with available experiments. Applying a recently developed scheme that combines DFT with quasiparticle energy calculations in the G0W0 approximation considerably improves defect energetics and gives gratifying agreement with experiment.