title: Heterogeneities and topological defects in two-dimensional pinned liquids.
abstract: We simulate a model of repulsively interacting colloids on a commensurate two-dimensional triangular pinning substrate where the amount of heterogeneous motion that appears at melting can be controlled systematically by turning off a fraction of the pinning sites. We correlate the amount of heterogeneous motion with the average topological defect number, time-dependent defect fluctuations, colloid diffusion, and the form of the van Hove correlation function. When the pinning sites are all off or all on, the melting occurs in a single step. When a fraction of the sites are turned off, the melting becomes considerably broadened and signatures of a two-step melting process appear. The noise power associated with fluctuations in the number of topological defects reaches a maximum when half of the pinning sites are removed and the noise spectrum has a pronounced 1 / f(alpha) structure in the heterogeneous regime. We find that regions of high mobility are associated with regions of high dislocation densities.
authors.affiliation: Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
authors.forename: J-X
authors.initials: JX
authors.lastname: Lin
authors.forename: C
authors.initials: C
authors.lastname: Reichhardt
authors.forename: Z
authors.initials: Z
authors.lastname: Nussinov
authors.forename: Leonid P
authors.initials: LP
authors.lastname: Pryadko
authors.forename: C J
authors.initials: CJ
authors.lastname: Olson Reichhardt