Time scale for the onset of Fickian diffusion in supercooled liquids

Grzegorz Szamel; Elijah Flenner

doi:10.1103/physreve.73.011504

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Time scale for the onset of Fickian diffusion in supercooled liquids

Grzegorz Szamel·Elijah Flenner

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Abstract

We propose a quantitative measure of a time scale on which Fickian diffusion sets in for supercooled liquids and use Brownian Dynamics computer simulations to determine the temperature dependence of this onset time in a Lennard-Jones binary mixture. The time for the onset of Fickian diffusion ranges between 6.5 and 31 times the $α$ relaxation time (the $α$ relaxation time is the characteristic relaxation time of the incoherent intermediate scattering function). The onset time increases faster with decreasing temperature than the $α$ relaxation time. Mean squared displacement at the onset time increases with decreasing temperature.

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Grzegorz Szamel, Elijah Flenner. 2005-08-03. Time scale for the onset of Fickian diffusion in supercooled liquids. https://doi.org/10.1103/physreve.73.011504

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