Molecular dynamics simulation of amorphous silica under pressures

Abstract

Models of amorphous silica have been produced at 500 K, and in pressures range GPa by molecular dynamics simulation. Topological analysis is performed based on the basic units and transition to different a-types, where a is the Oxx and Oxy (x, y = 4, 5, 6). The simulation shows that the fraction of different types of basic units varies strongly and the mid-range structure modifies stronger than the short-range structure under pressure. In the GPa pressure range, structure of amorphous silica occurs the transformation from D4-to D6 domain which correspond to the intervals of and GPa. We also found a number of O 456 connected with three different Si atoms. Upon compression, the structural change is accompanied with the transition and two parallel processes: merging and splitting of domains which relate to the change of domain-boundary atoms.