Cluster model of glass transition in simple liquids

TL;DR

This paper develops a microscopic statistical mechanics model to describe the glass transition in simple liquids, highlighting the role of cluster interactions and local structures like cubic and icosahedral clusters.

Contribution

It introduces a new cluster-based model of the glass transition, analyzing the sign change of interactions and the growth of the glass order parameter.

Findings

Cubic clusters freeze first upon cooling.

The transition temperature for icosahedral clusters is about 10% lower.

The local structure near the glass transition is likely cubic.

Abstract

On the basis of microscopic statistical mechanics of simple liquids the orientational interaction between clusters consisting of a particle and its nearest neighbors is estimated. It is shown that there are ranges of density and temperature where the interaction changes sign as a function of a radius of a cluster. The model of interacting cubic and icosahedral clusters is proposed and solved in mean-field replica symmetric approximation. It is shown that the glass order parameter grows smoothly upon cooling, the transition temperature being identified with the temperature of the replica symmetry breaking. It is shown that upon cooling a Lennard-Jones system, cubic clusters freeze first. The transition temperature for icosahedral clusters is about ten per cent lower. So the local structure of Lennard-Jones glass in the vicinity of glass transition should be most probably cubic.