Résumé:

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.

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