Structure in Sheared Supercooled Liquids: Dynamical Rearrangements of an Effective System of Icosahedra

TL;DR

This study links shear-induced structural rearrangements in supercooled liquids to an effective temperature framework based on icosahedral particle organization, revealing temperature differences in shear banding regions.

Contribution

It introduces a method to analyze shear effects in supercooled liquids using an effective system of icosahedra and correlates local effective temperatures with shear banding phenomena.

Findings

Effective temperature depends linearly on shear rate.

Shear banding results in distinct high and low temperature regions.

Global effective temperature aligns with weighted regional temperatures.

Abstract

We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics are correlated with the formation of particles organized into icosahedra under simple steady state shear. We recast this glassformer as an effective system of icosahedra [Pinney et al. J. Chem. Phys. 143 244507 (2015)]. From the observed population of icosahedra in each steady state, we obtain an effective temperature which is linearly dependent on the shear rate in the range considered. Upon shear banding, the system separates into a region of high shear rate and a region of low shear rate. The effective temperatures obtained in each case show that the low shear regions correspond to a significantly lower temperature than the high shear regions. Taking a weighted average of the effective temperature of these regions (weight determined by region size) yields an estimate of the effective temperature which compares well with an effective temperature based on the global mesocluster population of the whole system.