Issue
EPL
Volume 88, Number 5, December 2009
Article Number 58005
Number of page(s) 5
Section Interdisciplinary Physics and Related Areas of Science and Technology
DOI http://dx.doi.org/10.1209/0295-5075/88/58005
Published online 15 December 2009
EPL, 88 (2009) 58005
DOI: 10.1209/0295-5075/88/58005

Atomistic mechanism of physical ageing in glassy materials

M. Warren and J. Rottler

Department of Physics and Astronomy, The University of British Columbia - 6224 Agricultural Road, Vancouver, BC, V6T 1Z1, Canada

jrottler@phas.ubc.ca

received 14 July 2009; accepted in final form 16 November 2009; published December 2009
published online 15 December 2009

Abstract
Using molecular simulations, we identify microscopic relaxation events of individual particles in ageing structural glasses, and determine the full distribution of relaxation times. We find that the memory of the waiting time tw elapsed since the quench extends only up to the first relaxation event, while the distribution of all subsequent relaxation times (persistence times) follows a power law completely independent of history. Our results are in remarkable agreement with the well-known phenomenological trap model of ageing. A continuous-time random walk (CTRW) parametrized with the atomistic distributions captures the entire bulk diffusion behavior and explains the apparent scaling of the relaxation dynamics with tw during ageing, as well as observed deviations from perfect scaling.

PACS
81.05.Kf - Glasses (including metallic glasses).
64.70.Q- - Theory and modeling of the glass transition.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.

© EPLA 2009