Two-membered silicon rings on the dehydroxylated surface of silica

We present extensive modeling of the amorphous silica surface, aimed at con necting its structural and chemical features. beta-cristobalite surfaces ar e initially studied to model the hydroxylated surfaces. A model reconstruct ion of the (111) surface is used to define a path leading to the formation of two-membered silicon rings upon dehydroxylation. Subsequently, a realist ic model of the amorphous dehydroxylated (dry) surface is produced, by full ab initio annealing of an initial model generated by classical simulation. The presence of surface two-membered silicon rings emerges naturally. A ca lculation of IR activity yields an associated peak doublet in agreement wit h experimental data.