High-pressure densification of silica glass: A molecular-dynamics simulation

We have performed a molecular-dynamics simulation for a sample of amorphous SiO2 subject to a compression-decompression process at ambient temperature, using a recently proposed two-body potential model. For moderate compression the simulated glass maintains the ideal tetrahedral coordination and displays reversible elastic behavior. For compressions beyond 6 GPa, the glass becomes anelastic and its density and average atomic coordination increase irreversibly. Density, compressibility, and structure of the simulated material compare favorably with the experiments on both undensified and densified SiO2 glass. The stability of Si-O coordination greater than four in samples subject to high pressure appears to drive the densification process.