De-coupling of Exchange and Persistence Times in Atomistic Models of Glass Formers

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.