Void size distribution in MD-modelled silica glass structures

The void distribution of different models of the silica glass have been analyzed in terms of the Voronoi-Delaunay description of the void space into a disordered system. The silica glass has been modelled by making use of different pair-pair and three body potentials, previously proposed. The glass structural parameters (bond lengths and bond angles) are compared with known experimental data. A computer algorithm has been implemented to apply the Voronoi-Delaunay approach to a system of non-uniform spheres, and it is fully described. The algorithm furnishes the size distribution of interstices into the bulk structure. From this result, the solubility of noble gasses into the glass is computed, and the values obtained are successfully compared to known experimental data. The correlation between void size distribution and ring size distribution in silica glass is discussed. Both the glass structure and void distribution give better agreement to the experimental data when the pair pair interaction is modelled with the potential developed by Beest et al. [B.W.H. Beest, G.J. Kramer, R.A. Santen, Phys. Rev. Lett. 64 (1990) 1955].