Molecular Dynamics Modeling of SiO2 Melts and Glass Formation Processes

Molecular dynamics (MD) with ReaxFF potentials is used to study the melting process of quartz and cristobalite together with the amorphous structures obtained at different stages of melting by cooling the melt. The long-term preservation of an excess of eight-membered rings inherited from the crystalline phase is found in the quartz melts, while in the cristobalite melts, the similar preservation of six-membered rings is not observed. Thus, it can be stated that the quartz melts and glasses obtained from them have structural memory, in contrast to cristobalite melts. An increase in the number of four-membered rings with increasing temperature is revealed. A number of other features of the obtained amorphous structures, which we consider as models for glasses, are discussed.