Energy barriers, entropy barriers, and non-Arrhenius behavior in a minimal glassy model

TL;DR

This study investigates the glassy dynamics of a minimal model with three particles, revealing how energy and entropy barriers influence non-Arrhenius behavior near the glass transition.

Contribution

It introduces a simple three-particle model to analyze the combined effects of energy and entropy barriers on glassy dynamics.

Findings

Free energy landscape with two minima and a barrier governs rearrangements.

Both potential energy and entropy contribute to the free energy barrier.

Barrier heights depend on temperature and system size, explaining non-Arrhenius behavior.

Abstract

We study glassy dynamics using a simulation of three soft Brownian particles confined to a two-dimensional circular region. If the circular region is large, the disks freely rearrange, but rearrangements are rarer for smaller system sizes. We directly measure a one-dimensional free energy landscape characterizing the dynamics. This landscape has two local minima corresponding to the two distinct disk configurations, separated by a free energy barrier which governs the rearrangement rate. We study several different interaction potentials and demonstrate that the free energy barrier is composed of a potential energy barrier and an entropic barrier. The heights of both of these barriers depend on temperature and system size, demonstrating how non-Arrhenius behavior can arise close to the glass transition.