Simulated Crystallite Melting Kinetics in Two Dimensions

ORAL

Abstract

We report on results of numerical simulations of the melting of two-dimensional crystallites. Recent experiments in colloidal systems demonstrate that colloidal crystallites undergo a two-stage melting process. Initially large crystallites melt at a constant rate until reaching a critical size at which there is a dramatic increase in the melting rate. Throughout the initial melting stage the crystallite interior maintains bond orientational order; this order is abruptly lost at the critical size. Using Brownian dynamics simulations of particles interacting via a variety of short-range central potentials, we find that in two dimensions small crystallites generically melt in two-stages characterized by a sudden increase in melting rate that coincides with an abrupt loss of bond orientational order. The critical size, particle number ${\cal O}(20)$, is in agreement with experimental data and appears insensitive to details of the short-range interparticle potential. We discuss a possible mechanism for this change in melting dynamics at a critical crystallite size. This work is supported in part by NSF (DMR-0242402) and NASA (NAG8-1659).

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Authors

  • D. W. Blair

  • J.R. Savage

  • Anthony Dinsmore

    • University of Massachusetts, Amherst
    • University of Massachusetts Amherst Physics
    • University of Massachusetts at Amherst

  • J. Machta

    • University of Massachusetts Amherst
    • University of Massachusetts at Amherst

  • R. A. Guyer

    • University of Massachusetts at Amherst

  • Alex Levine

    • UCLA
    • University of California, Los Angeles
    • Department of Chemistry and Biochemistry, University of California, Los Angeles
    • UCLA Department of Chemistry and Biochemistry
    • Department of Chemistry, University of California at Los Angeles, Los Angeles, CA 90095
    • Department of Chemistry and Biochemistry, University of California, Los Angeles, California