| The work presented in this thesis consists of using computational methods to understand the nature of vitreous silica at high pressure, predict the possible atomistic processes that lead to the densification in this glass, and examine the implications these structural modification have on selected useful properties. These simulations are part of an effort required to develop realistic models of this technologically important glass.; Vitreous silica is simulated on the atomic-scale at elevated pressures using two computational tools. First, we reproduce realistic models of pure vitreous silica. Next, we monitor the behavior of this glass under shock pressures using molecular dynamics (MD) simulations. The simulations reproduce the experimental equation of state (EOS) of this material and explain its characteristic dependence on pressure. It is found that shock pressures modify the medium-range order of this amorphous system, producing changes that are revealed by its ring size distribution. The ring size distribution remains unchanged during elastic compression but varies continuously after the transition to the plastic regime. A detailed analysis of key structural parameters indicates the mechanisms that lead to such transformations in vitreous silica. Finally, we perform first-principles calculations to investigate the role of selected defects in the degradation of the optical properties in densified vitreous silica. |
