MOLECULAR-DYNAMICS SIMULATION OF SILICA LIQUID AND GLASS

A molecular dynamic computer simulation of the cooling of liquid silica to form an amorphous solid (glassy) phase was performed using the potential of Tsuneyuki, Tsukuda, Aoki, and Matsui, which was found to be consistent with the structure of several crystalline phases of silica. In the simulations, at low temperatures the atoms formed an almost perfect random tetrahedral network, and on subsequent annealing the material formed a perfect network, with each silicon having four oxygen neighbors and each oxygen having two silicon neighbors. The simulated material at low temperatures has a structure that is in close agreement with experimental neutron scattering measurements on amorphous silica. Several proper-ties of the material were calculated and compared with experiment, and the nature of the "inherent structure" of the material as a function of temperature was investigated. The potential of Tsuneyuki et al. provides an excellent model for amorphous silica as well as crystalline silica.