Structural and Dynamical Correlations in Stishovite and High Density Silica Glass

Pressure-induced structural transformation from tetrahedral to octahedral coordination and the destruction of intermediate-range order (IRO) are studied in silica glass (a-SiO2) using the molecular-dynamics (MD) method. Changes in the position and height of the first sharp diffraction peak (FSDP) in the static structure factor, bond lengths, coordination numbers, bond-angle distributions, and statistics of rings are investigated as a function of density. Modifications of the vibrational density of states and participation ratio are also discussed.