Generation of glass SiO2 structures by various cooling rates: A molecular-dynamics study

Molecular-dynamics (MD) simulations using the modified parameters of the Tersoff interatomic potential have been performed to investigate the change of the structural and dynamical properties of glass SiO2 with various cooling rates. Although the properties and atomic configurations of glass formed by a fast cooling rate of ∼1013 K/s could be reproduced well, they contained more structural defects. The local order and coordination defect of system increases with decreasing cooling rate. The origin of atomic structural change and the bond angle distribution is understood on the basis of corner-sharing and edge-sharing tetrahedral structures. Results of the phonon density of states also exhibit a dependence on the cooling rates. When the cooling rate is decreased, the spectrum of the glass SiO2 shifts toward the higher frequencies due to the higher bending frequency.