Dynamics of a rod in a random static environment: non-Gaussian behaviour on large length scales

Abstract

We present molecular dynamics simulations of the motion of a single rod in a two-dimensional random static array of discs. For long rods the mean-squared displacement of the centre of mass shows a cage effect similar to that observed in supercooled liquids or dense colloidal systems. We have determined the time-dependence of the non-Gaussian parameter for different rod lengths. It is found that the long-time regime is strongly non-Gaussian even on length scales of the order of 10–15 times the rod length, thus showing the heterogeneity of the dynamics on such length scales.

Acknowledgements

We are grateful to E. Frey for useful discussions. A. J. M. acknowledges a post-doctoral grant from the Basque Government.