Aging effects in supercooled silica. A molecular dynamics investigation

Using molecular dynamics simulations we investigate the presence of dynamical heterogeneities in supercooled silica, a 'strong' glass former, and the changes as a function of time of these heterogeneities during aging. We compare the radial distribution functions for the 10% most mobile silicon or oxygen atoms with the corresponding mean radial distribution functions. We measure changes of these radial distribution functions and the changes of the non-gaussian parameters with time after a quench. We find that dynamical heterogeneities are present in silica and that they increase during the aging process. We find that the oxygen and silicon atoms show similar heterogeneities but with a differing rate of change during aging. (C) 2003 Elsevier B.V. All rights reserved.