paper

Heterogeneous Diffusion in Highly Supercooled Liquids

arXiv:cond-mat/9807180 · doi:10.1103/PhysRevLett.81.4915

Abstract

The diffusivity of tagged particles is demonstrated to be very heterogeneous on time scales comparable to or shorter than the relaxation time ( the stress relaxation time) in a highly supercooled liquid via 3D molecular dynamics simulation. The particle motions in the relatively active regions dominantly contribute to the mean square displacement, giving rise to a diffusion constant systematically larger than the Einstein-Stokes value. The van Hove self-correlation function is shown to have a long distance tail which can be scaled in terms of for $t \ls 3τ_α$. Its presence indicates heterogeneous diffusion in the active regions. However, the diffusion process eventually becomes homogeneous on time scales longer than the life time of the heterogeneity structure ().

4 pages, 5 figures

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