Kinetic heterogeneities at dynamical crossovers
Department of Physics and Astronomy, University of Pennsylvania - Philadelphia, PA 19104, USA
Accepted: 10 June 2010
We perform molecular dynamics simulations of a model glass-forming liquid to measure the size of kinetic heterogeneities, using a dynamic susceptibility χss(a, t) that quantifies the number of particles whose dynamics are correlated on the length scale a and time scale t. By measuring χss(a, t) as a function of both a and t, we locate local maxima χ⋆ at distances a⋆ and times t⋆. Near the dynamical glass transition, we find two types of maxima, both correlated with crossovers in the dynamical behavior: a smaller maximum corresponding to the crossover from ballistic to sub-diffusive motion, and a larger maximum corresponding to the crossover from sub-diffusive to diffusive motion. Our results indicate that kinetic heterogeneities are not necessarily signatures of an impending glass or jamming transition.
PACS: 64.70.Q- – Theory and modeling of the glass transition / 64.70.pm – Glass transitions of specific systems: Liquids / 64.70.ps – Glass transitions of specific systems: Granules
© EPLA, 2010