Structural-dynamical transition in the Wahnstr\"om mixture

TL;DR

This paper investigates a dynamical phase transition in glass-forming liquids, linking local structural order, especially icosahedral arrangements, to dynamical heterogeneities and mechanical rigidity in a Lennard-Jones mixture.

Contribution

It demonstrates how structural and dynamical observables influence the dynamical phase transition in trajectory space of glass-forming liquids.

Findings

The inactive phase is rich in icosahedral order.

Structural order correlates with mechanical rigidity.

Choice of observables affects the observed transition.

Abstract

In trajectory space, dynamical heterogeneities in glass-forming liquids correspond to the emergence of a dynamical phase transition between an active phase poor in local structure and an inactive phase which is rich in local structure. We support this scenario with the study of a model additive mixture of Lennard-Jones particles, quantifying how the choice of the relevant structural and dynamical observable affects the transition in trajectory space. We find that the low mobility, structure-rich phase is dominated by icosahedral order. Applying a nonequilibrium rheological protocol, we connect local order to the emergence of mechanical rigidity.