Molecular dynamics simulations of glasses

We present MD simulations of two glass-forming structures (Se and SiO(2)) at temperatures above and below the glass transition. In both structures we find the relaxations to be localized on a small number of atoms. However, both the number of atoms involved in jumps and the jump-length grow with temperature. In Se the relaxing units form typically chain-like structures. In the simulations of SiO(2)-glasses we observe that the displacement of the oxygen is larger than the corresponding Si contribution. In these cases the relaxations occur predominantly at atoms which are topological defects (under- or rarely over-coordinated). (C) 1999 Elsevier Science B.V. All rights reserved.