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arXiv · 1006.4422

Subdiffusion and intermittent dynamic fluctuations in the aging regime of concentrated hard spheres

Djamel El Masri·Ludovic Berthier·Luca Cipelletti
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Abstract

We study the nonequilibrium aging dynamics in a system of quasi-hard spheres at large density by means of computer simulations. We find that, after a sudden quench to large density, the relaxation time initially increases exponentially with the age of the system. After a surprisingly large crossover time, the system enters the asymptotic aging regime characterized by a linear increase of the relaxation time with age. In this aging regime, single particle motion is strongly non-Fickian, with a mean-squared displacement increasing subdiffusively, associated to broad, non-Gaussian tails in the distribution of particle displacements. We find that the system ages through temporally intermittent relaxation events, and a detailed finite size analysis of these collective dynamic fluctuations reveals that these events are not spanning the entire system, but remain spatially localized.

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Djamel El Masri, Ludovic Berthier, Luca Cipelletti. 2010-06-23. Subdiffusion and intermittent dynamic fluctuations in the aging regime of concentrated hard spheres. https://doi.org/10.1103/physreve.82.031503

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