Large heat-capacity jump in cooling-heating of fragile glass from kinetic Monte Carlo simulations based on a two-state picture

TL;DR

This study uses kinetic Monte Carlo simulations of a two-state particle model to explain the large heat capacity jump and hysteresis observed in fragile glasses during cooling and heating cycles.

Contribution

It demonstrates that a two-state particle interaction model can reproduce experimental heat capacity features of fragile glasses, highlighting the role of energy state transfer.

Findings

Reproduces large $c_v$ and hysteresis in fragile glasses

Shows transfer of probabilistic weight from high to low energy states

Provides insight into the microscopic origin of heat capacity anomalies

Abstract

The specific heat capacity $c_v$ of glass formers undergoes a hysteresis when subjected to a cooling-heating cycle, with a larger $c_v$ and a more pronounced hysteresis for fragile glasses than for strong ones. Here, we show that these experimental features, including the unusually large magnitude of $c_v$ of fragile glasses, are well reproduced by kinetic Monte Carlo and equilibrium study of a distinguishable particle lattice model (DPLM) incorporating a two-state picture of particle interactions. The large $c_v$ in fragile glasses is caused by a dramatic transfer of probabilistic weight from high-energy particle interactions to low-energy ones as temperature decreases.