The dynamics and structure heterogeneity of aluminum-silicate melts: Molecular dynamics simulation

We have performed a new analysis on the dynamics and structure to investigate the aluminum-silicate melt under pressure. It is shown that the low-pressure configuration of the melt exhibits dynamic heterogeneity. The mobile and immobile atoms tend to reside in regions which have extremely high or low density. We reveal two moving types: the simply hopping or collective moving via supermolecule. The latter type is responsible for the positive pressure dependence on diffusivity. The structure is analyzed via SC-particle and SC-cluster. Our simulation reveals the structural heterogeneity in local environment and chemical composition. The densification of the melt is accompanied with the decreasing of the radius of core of SC-particle and the number of large SC-particles. We found that the liquid comprises two types of SC-particles. The SC-clusters of second type form large space regions which represent the diffusion pathway for aluminum.