Study of the effect of sizes on the structural properties of SiO2 glass by molecular dynamics simulations

To validate the present model and different simulation results of SiO2 considering 169,956 atoms, the total correlation function of solid SiO2 obtained by the present simulation is compared with that of the experimental results obtained by Poulsen et al. [14] and agrees well with the experimental results. To understand the effect of model size on the physical and chemical properties of solid SiO2, SiO2 is formed using four different sizes of model considering the total number of Si and 0 atoms 666, 5808, 169,956 and 339,915 in the ratio 1:2 using the parameters of Si-Si, Si-O, and O-O in Tersoff potential obtained by Munetoh et al. [40] by the molecular dynamics simulations. The effect of model sizes on the partial radial distribution functions of Si-Si, Si-O, and O-O with the total radial distribution function of solid SiO2 as a function of radial distance is studied. Besides, the effect of model sizes on the bond angle distribution of Si-O-Si and O-Si-O with angle, and bond density of Si-Si, Si-O, and O-O in solid SiO2 as a function of radial distance is studied. All of the physical and chemical properties in liquid and solid states of SiO2 are studied during the simulation of SiO2 considering 169,956 atoms and if the model size is increased beyond this size, no size effect is observed on the physical and chemical properties of SiO2. The obtained physical and chemical properties like partial radial distribution functions of Si-Si, Si-O, and O-O and total radial distribution function of liquid and solid SiO2, angle distribution of O-Si-O and Si-O-Si in the liquid and solid phases during the simulation considering 169,956 atoms are compared with those of Munetoh et al. [40] and others, and are highlighted as the major limitations of the results of Munetoh et at [40] and others, and are shown as the superiority of the present simulation results. Details of the bond density of Si-Si, Si-O, and O-O at the liquid and solid phases with bond distance are described. Details of the phase transformation of SiO2 glass are described with the help of graphical representations. The effects of pressure and temperature on the physical and chemical properties of SiO2 (alpha-quartz) are described with the graphical results. Due to high pressure alpha-quartz is converted into coesite which is discussed. (C) 2013 Elsevier B.V. All rights reserved.