Spatial correlation of the dynamic propensity of a glass-forming liquid

Abstract

We present computer simulation results on the dynamic propensity (as defined byWidmer-Cooper et al 2004 Phys. Rev. Lett. 93 135701) in a Kob–Andersen binary Lennard-Jonesliquid system consisting of 8788 particles. We compute the spatial correlationfunction for the dynamic propensity as a function of both the reduced temperatureT, and the time scale on which the particle displacements are measured. ForT ≤ 0.6, we find that non-zero correlations occur at the largest length scale accessiblein our system. We also show that a cluster-size analysis of particles withextremal values of the dynamic propensity, as well as 3D visualizations,reveal spatially correlated regions that approach the size of our system asT decreases, consistently with the behavior of the spatial correlation function. Next, we defineand examine the ‘coordination propensity’, the isoconfigurational average of thecoordination number of the minority B particles around the majority A particles. We showthat a significant correlation exists between the spatial fluctuations of the dynamic andcoordination propensities. In addition, we find non-zero correlations of the coordinationpropensity occurring at the largest length scale accessible in our system for allT in therange 0.466 < T < 1.0. We discuss the implications of these results for understanding the length scales ofdynamical heterogeneity in glass-forming liquids.