Microscopic structure and dynamics of glass like domains in a low density binary mixture

Abstract

We present results from extensive equilibrium molecular dynamic simulations of a binary Lennard Jones 80:20 mixture. Our study focuses on the changes in structural and dynamic properties of this system during its transition from a stable phase to an unstable phase as temperature reduces. This system, phase separate into a mixture of glass like domains and gas at lowest temperatures. We compute coarse-grained density(CGD) to identify density distribution in the system, which shows formation of very dense domains. Studies of bond order parameter shows a mixture of crystal structures in these domains at low temperatures. These results show that the structure of the dense domains formed at low density is akin to glassy domains that is found in studies of glass transition at high density, at low temperatures. Our studies on mean square displacement of particles at various state points shows pronounced sub-diffusive regime and plateau that marks the existence of dynamic arrest due to cage formation known in the studies of glassy and supercooled liquids.