Density functional calculations, using an α-quartz super-cell as a model silica host, identified the peroxy linkage as being the lowest-energy configuration of atomic O in the oxide. It was found that its energy in this site, and in interstitial molecular O2, were almost equal. By using ab initio molecular dynamics, modified so as to converge to a saddle-point, the barrier to concerted exchange of the peroxy linkage was found to be 1.3eV. Although O was generally believed to diffuse in molecular form in this oxide, the measured diffusion activation energies were more consistent with the peroxy exchange barrier.

Diffusion of Atomic Oxygen in SiO2. D.R.Hamann: Physical Review Letters, 1998, 81[16], 3447-50