Model for dynamics of structural glasses

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Abstract
We have studied, using dynamical Monte Carlo methods, a facilitated kinetic Ising model for structural glasses. We observe stretched-exponential decays (α relaxation) of the equilibrium spin autocorrelation function at late times and are able to estimate accurately the corresponding relaxation times τ. These are found to diverge at nonzero temperatures following a Vogel-Fulcher law. In addition, we observe early-time exponential relaxation analogous to Β relaxation of glass formers. We also examined the effective thermodynamics of systems quenched below this divergent temperature and subsequently heated. The result is a peak in the specific heat with properties matching those of the putative glass transition. We also find that these peaks, for different heating rates, can be rescaled to lie on a universal curve. Finally, we studied the evolving structure factor of a frozen glass following a rapid jump in temperature. The results are qualitatively the same as those for x-ray studies of heated glasses. We thus demonstrate that this purely dynamical microscopic model can reproduce much of the phenomenology of the glass transition and near-glass relaxation, with no tunable parameters.