Publication Title

Physical Review Letters

Publication Date

1-24-2013

Document Type

Article

DOI

10.1103/PhysRevLett.110.047801

Keywords

2 dimensions, transition, diffusion, liquids, systems, order

Disciplines

Physics

Abstract

A two-dimensional (2D) solid lacks long-range positional order and is diffusive by means of the cooperative motion of particles. We find from molecular dynamics simulations of hard discs that 2D colloids in solid and hexatic phases show seemingly Fickian but strongly heterogeneous dynamics. Beyond translational relaxation time, the mean-square displacement is linear with time, t, implying that discs would undergo Brownian diffusion and the self-part of the van Hove correlation function [G(s)(r, t)] might be Gaussian. But dynamics is still heterogeneous and G(s)(r, t) is exponential at large r and oscillatory with multiple peaks at intermediate length. We attribute the existence of several such peaks to the observation that there are several clusters of discs with discretized mobility. The cluster of marginally mobile discs grows with time and begins to percolate around translational relaxation time while clusters of fast discs emerge in the middle of the marginally mobile cluster.

Comments

Copyright 2013 American Physical Society. Available on publisher's site at http://dx.doi.org/10.1103/PhysRevLett.110.047801

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