title: Simulation study of seemingly Fickian but heterogeneous dynamics of two dimensional colloids.
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.
authors.affiliation: Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
authors.forename: Jeongmin
authors.initials: J
authors.lastname: Kim
authors.affiliation: Chemical Physics Interdisciplinary Program and Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
authors.forename: Chanjoong
authors.initials: C
authors.lastname: Kim
authors.affiliation: Department of Chemistry, Sogang University, Seoul 121-742, Republic of Korea.
authors.forename: Bong June
authors.initials: BJ
authors.lastname: Sung
mesh_terms: D003102:Colloids / Q000737:chemistry*; D003198:Computer Simulation; D008956:Models, Chemical
chemical_list: D003102:Colloids