Localized mechanical instabilities and structural transformations in silica glass under high pressure

Molecular simulations show that the structural transformations which occur in silica glass under high pressure do not require thermal activation, and arise from localized mechanical instabilities associated with disappearances of local minima on the potential energy surface. This result leads to the prediction that the kinetic stability of silica glass structures differs from that of silica crystal structures: The glass will undergo a pressure-induced transformation to a structure with high average silicon coordination at any arbitrarily low temperature, but this glass structure with high average coordination can never be quenched to atmospheric pressure.