Molecular Dynamics Simulation of the Correlation Between Structural and Dynamics Heterogeneity at Higher Temperatures in SiO\(_2\) Liquid

Abstract

In this paper, we present the results of a molecular dynamics simulation for SiO2 liquid to study the correlation between structural and dynamics heterogeneity. The evolution of structural changes at higher temperatures has been analyzed through the help of the SiOx- and OSiy units/clusters, bond angle distribution, Voronoi polyhedrons features and specified set of atoms. The result shows that SiO2 liquid comprises a tetrahedral-network, some small SiO5-, SiO6-clusters and boundary region atoms which strongly depends on temperature. As temperature increases, the SiO4-, SiO5- and SiO6 units become more distorted. Voronoi polyhedrons radius distribution of atoms is well fitted to a Gaussian form. We investigate the 10% most mobile (SMA) and 10% most immobile (SIMA) atoms in the system. We found that mobile or immobile atoms are non-uniformly distributed, forming spatially distinct mobile and immobile regions. These atoms form clusters whose size grows rapidly with temperature decreasing. The self diffusion pathway is explained by the movement of the small SiOx-clusters, and bond-breaking Si-O in tetrahedral-network to form SiO5-, SiO6 clusters and boundary region atoms distributed heterogeneously (DH) in the network-forming liquid.