  With molecular dynamics simulations of a fluid mixture of classical particles
interacting with pair-wise additive Weeks-Chandler-Andersen potentials, we
consider the time series of particle displacements and thereby determine
distributions for local persistence times and local exchange times. These basic
characterizations of glassy dynamics are studied over a range of super-cooled
conditions and shown to have behaviors, most notably de-coupling, similar to
those found in kinetically constrained lattice models of structural glasses.
Implications are noted.
