Aspects of point defects energetics and diffusion in SiO2 from first principles simulations

Diffusion properties are crucial for the simulation of post-irradiation evolution of materials and the structural and energetic peculiarities of point defects themselves should help us to understand the behavior of silica glasses under irradiation. Starting from a systematic first principles study of native point defects formation and migration energies in crystalline and amorphous silicon dioxide, we discuss the influence of the electron chemical potential and charge compensation on the dominant species contributing to oxygen self-diffusion in closed mode. We present then some results concerning the interaction of hydrogen impurities with oxygen interstitials in quartz and show that hydrogen passivation of oxygen interstitials is expected to occur; the consequences for oxygen self-diffusion cannot be overlooked