Liquid-liquid phase transition and anomalous diffusion in simulated liquid GeO2

Abstract

We perform molecular dynamics (MD) simulation of diffusion in liquid GeO2 at the temperatures ranged from 3000 to 5000 K and densities ranged from 3.65 to 7.90 g/cm3. Simulations were done in a model containing 3000 particles with the new interatomic potentials for liquid and amorphous GeO2, which have weak Coulomb interaction and Morse-type short-range interaction. We found a liquid-liquid phase transition in simulated liquid GeO2 from a tetrahedral to an octahedral network structure upon compression. Moreover, such phase transition accompanied with an anomalous diffusion of particles in liquid GeO2 that the diffusion constant of both Ge and O particles strongly increases with increasing density (e.g. with increasing pressure) and it shows a maximum at the density around 4.95 g/cm3. The possible relation between anomalous diffusion of particles and structural phase transition in the system has been discussed. © 2006 Elsevier B.V. All rights reserved.