Cooling Rate Dependence and Dynamic Heterogeneity Below the Glass Transition in a Lennard-Jones Glass

TL;DR

This study uses molecular dynamics simulations to explore how cooling rate affects the glass transition and heterogeneity in a Lennard-Jones glass, revealing that slower cooling leads to lower enthalpy and increased local order, with dynamic heterogeneity observed during melting.

Contribution

It provides a detailed analysis of the cooling rate dependence and dynamic heterogeneity in Lennard-Jones glasses through extensive simulations.

Findings

Slower cooling results in lower enthalpy and higher local order.

Dynamic heterogeneity exists with immobile and mobile particles in different local environments.

Cooling rate influences the temperature at which the system falls out of equilibrium.

Abstract

We investigate a binary Lennard-Jones mixture with molecular dynamics simulations. We consider first a system cooled linearly in time with the cooling rate gamma. By varying gamma over almost four decades we study the influence of the cooling rate on the glass transition and on the resulting glass. We find for all investigated quantities a cooling rate dependence; with decreasing cooling rate the system falls out of equilibrium at decreasing temperatures, reaches lower enthalpies and obtains increasing local order. Next we study the dynamics of the melting process by investigating the most immobile and most mobile particles in the glass. We find that their spatial distribution is heterogeneous and that the immobile/mobile particles are surrounded by denser/less dense cages than an average particle.