Yael S. Elmatad, Aaron S. Keys
By characterizing the dynamics of idealized lattice models with a tunable
kinetic constraint, we explore the different ways in which dynamical
facilitation manifests itself within the local dynamics of glassy materials.
Dynamical facilitation is characterized both by a mobility transfer function,
the propensity for highly-mobile regions to arise near regions that were
previously mobile, and by a facilitation volume, the effect of an initial
dynamical event on subsequent dynamics within a region surrounding it.
Sustained bursts of dynamical activity -- avalanches -- are shown to occur in
kinetically constrained models, but, contrary to recent claims, we find that
the decreasing spatiotemporal extent of avalanches with increased supercooling
previously observed in granular experiments does not imply diminishing
facilitation. Viewed within the context of existing simulation and experimental
evidence, our findings show that dynamical facilitation plays a significant
role in the dynamics of systems investigated over the range of state points
accessible to molecular simulations and granular experiments.
View original:
http://arxiv.org/abs/1202.5527
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