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.Comment: 4pages, 6figure