Ab initio calculations of H+ energetics in SiO2: Implications for transport

The process of H+ diffusion in SiO2 is studied using first principles densi ty-functional theory. This is done by examining stable bonding sites, migra tion pathways, and barrier heights of H+ in alpha-quartz. The H+ is found t o bind to the bridging oxygen site in a variety of ways, but always display ing an attraction to neighboring oxygen atoms; This attraction provides a m echanism for understanding the diffusion pathways and barrier heights for t his system. The relative stability of H+ in SiO2 is also discussed in the c ontext of transport.