Signature of dynamical heterogeneity in spatial correlations of particle displacement and its temporal evolution in supercooled liquids

Abstract

The existence of heterogeneity in the dynamics of supercooled liquids is believed to be one of the hallmarks of the glass transition. Intense research has been carried out in the past to understand the origin of this heterogeneity in dynamics and a possible length scale associated with it. We have done extensive molecular dynamics simulations of a few model glass-forming liquids in three dimensions to understand the temporal evolution of the dynamic heterogeneity and the heterogeneity length scale. We find that although the strength of the dynamic heterogeneity is maximum at a timescale close to the characteristic α-relaxation time of the system, dynamic heterogeneity itself is well developed at a timescale as short as the β-relaxation time and survives up to a timescale as long as a few tens of the α-relaxation time. Moreover, we discovered that the temperature dependence of the heterogeneity length remains the same in the whole time window, in agreement with the inhomogeneous mode-coupling theory, although its absolute value changes over time in a nonmonotonic manner.