Surface induced anomalous glassy relaxation in phase separated Lennard-Jones liquid

Abstract

We have performed molecular simulation studies to understand the slowdown of relaxation process of pure Lennard-Jones system in the phase separated regime at two number densities 0.2 and 0.6. As temperature is lowered, these systems phase separate into gas and liquid and on further cooling it become dense glassy and gas domains or it crystallizes. We have studied the structure and dynamics of these metastable long lived domains that are formed at low number densities and lowest temperatures to see the effect of number density in crystal and glass formation. The structures found from radial distribution function at intermediates temperatures shows features of secondary local structure commonly seen in the studies of supercooled liquids. We characterized the dynamic heterogeneity inside the dense domains formed at low temperatures in this system from mean square displacements and incoherent intermediate scattering functions. This work presents that slowdown of the dynamics is strongly correlated with formation of local structures and relaxation process akin to glass forming liquids. The glassiness of the domains formed is enhanced at lower number density due to the surfaces that result in incomplete crystal structures.