Polyamorphism in the silica glass

A molecular dynamics (MD) simulation has been carried out to explore the polymorphic states of silica glass under ambient pressure. We show for the first time that the simulated glass is composed of atomic clusters of type C4, C5 and C6. Densification is performed via gradual variation in the volume of those clusters. The total volume of the MD model and the void volume are found to be a linear function of the fraction of SiOx units with x = 4, 5 and 6.