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Dynamic heterogeneity and non-Gaussian behavior in a model supercooled liquid

M. Scott Shell·Pablo G. Debenedetti·Frank H. Stillinger
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Abstract

We use a recently-derived reformulation of the diffusion constant [Stillinger F H and Debenedetti P G 2005 J. Phys. Chem. B 109 6604] to investigate heterogeneous dynamics and non-Gaussian diffusion in a binary Lennard-Jones mixture. Our work focuses on the joint probability distribution of particles with velocity v_0 at time t=0 and eventual displacement Delta x at time t=Delta t. We show that this distribution attains a distinctive shape at the time of maximum non-Gaussian behavior in the supercooled liquid. By performing a two-Gaussian fit of the displacement data, we obtain, in a non-arbitrary manner, two diffusive length scales inherent to the supercooled liquid and use them to identify spatially separated regions of mobile and immobile particles.

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M. Scott Shell, Pablo G. Debenedetti, Frank H. Stillinger. 2005-06-23. Dynamic heterogeneity and non-Gaussian behavior in a model supercooled liquid. https://doi.org/10.1088/0953-8984%2F17%2F49%2F002

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