Lifetime of dynamical heterogeneity in a highly supercooled liquid

Abstract

We numerically examine dynamical heterogeneity in a highly supercooled three-dimensional liquid via molecular-dynamics simulations. To define the local dynamics, we consider two time intervals: τα and τngp. τα is the α relaxation time, and τngp is the time at which non-Gaussian parameter of the Van Hove self-correlation function is maximized. We determine the lifetimes of the heterogeneous dynamics in these two different time intervals, τhetero(τα) and τhetero(τngp), by calculating the time correlation function of the particle dynamics, i.e., the four-point correlation function. We find that the difference between τhetero(τα) and τhetero(τngp) increases with decreasing temperature. At low temperatures, τhetero(τα) is considerably larger than τα, while τhetero(τngp) remains comparable to τα. Thus, the lifetime of the heterogeneous dynamics depends strongly on the time interval.