Following microscopic motion in a two dimensional glass-forming binary fluid

TL;DR

This study investigates the microscopic dynamics of a binary glass-forming fluid using Voronoi topology, revealing a transition from fluid-like to localized motion as temperature decreases, with implications for understanding dynamical heterogeneities.

Contribution

It introduces a topological analysis method to study particle motion in glass-forming liquids, highlighting changes in dynamics near the glass transition.

Findings

High-temperature dynamics dominated by fluid-like motion.

Low-temperature dynamics show localized motion in specific topologies.

Particles can translate without changing their local topology.

Abstract

The dynamics of a binary mixture of large and small discs are studied at temperatures approaching the glass transition using an analysis based on the topology of the Voronoi polygon surrounding each atom. At higher temperatures we find that dynamics is dominated by fluid-like motion that involves particles entering and exiting the nearest-neighbour shells of nearby particles. As the temperature is lowered, the rate of topological moves decreases and motion becomes localised to regions of mixed pentagons and heptagons. In addition we find that in the low temperature state particles may translate significant distances without undergoing changes in their nearest neig hbour shell. These results have implications for dynamical heterogeneities in glass forming liquids.