Amorphous silica from the Rigid Unit Mode approach

We apply the Rigid Unit Mode model, which was initially developed for crystalline silicates, to the study of the flexibility of silica glass. Using a density-of-states approach we show that silica glass has the same flexibility against infinitesimal displacements of crystalline phases. Molecular dynamics simulations also show that parts of the silica structure are able to undergo large spontaneous changes through reorientations of the SiO4 tetrahedra with no energy cost.