Based upon gradient corrected periodic density functional theory, the formation,

structure and diffusion of SiO pairs in a-SiO2 was considered. It was found that a

SiO pair preferentially underwent transformation into an O vacancy via a twofoldcoordinated

Si atom. The pathways for SiO pair → divalent Si → O vacancy

transformation and divalent Si diffusion, together with O vacancy diffusion, were

determined. Based upon these results, it was also suggested how the presence of

SiO pairs could enhance Si self-diffusion in a-SiO2.

Structure and Dynamics of Silicon-Oxygen Pairs and Their Role in Silicon Self-

Diffusion in Amorphous Silica. C.L.Kuo, S.Lee, G.S.Hwang: Journal of Applied

Physics, 2008, 104[5], 054906