The diffusion of O2 in SiO2 was considered, using first-principles spin-polarized total-energy calculations. It was found that the potential energy surfaces for the singlet and triplet states were very different in certain regions, and that the O2 molecule preserved its spin-triplet ground state; not only at its most stable interstitial position within the solid, but also throughout its diffusion pathway. It was therefore concluded that the singlet state was not a good approximation for describing the behavior of O2 in SiO2, and that spin-polarization effects were fundamental to an understanding of the properties of this system.

O2 Diffusion in SiO2 - Triplet versus Singlet. W.Orellana, A.J.R.Da Silva, A.Fazzio: Physical Review Letters, 2001, 87[15], 155901 (4pp)