Eur. Phys. J. B 71, 105-110 (2009)
https://doi.org/10.1140/epjb/e2009-00276-2

Simulation study of polymorphism and diffusion anomaly for SiO₂ and GeO₂ liquid

Department of Computational Physics, Hanoi University of Technology, Hanoi, Vietnam

Corresponding author: ^a pkhung@fpt.vn

Received: 17 March 2009
Revised: 9 June 2009
Published online: 11 August 2009

Abstract

We report molecular dynamic (MD) simulations of a silica and germania liquid. We show for the first time that the liquid models constructed of the BKS and Ocffner-Elliott potential are composed of D₄, D₅ and D₆ domains. These domains of different liquids (identical chemical composition but different density) are structurally identical. The liquid densification occurs gradually with variation in the volume of the D₄, D₅ and D₆ domains. The void radius distributions (VRD) have been computed and they are well fitted to a Gaussian form. Both the average void radii and width of the VRD decrease with pressure. The diffusivity of Si/Ge or O depends linearly on the fraction of TO_x (x = 4, 5 and 6; T is Ge or Si). The diffusion anomaly results from the very high mobility of silicon in the D₅ domain compared to domains D₄ and D₆.