Locally favoured structures and dynamic length scales in a simple glass-former

TL;DR

This study examines the static and dynamic properties of a supercooled hard sphere system, revealing the emergence of locally favoured structures and analyzing the shape and size growth of dynamically heterogeneous regions.

Contribution

It introduces a new method to analyze the shape of dynamic heterogeneity regions, providing insights into their growth and relation to structural features in glass-formers.

Findings

Emergence of icosahedral locally favoured structures in supercooled states

Shape of dynamically heterogeneous regions changes weakly with supercooling

Four-point correlation length may grow faster than the shape-based measure

Abstract

We investigate the static and dynamic properties of a weakly polydisperse hard sphere system in the deeply supercooled state, i.e. at densities higher than that corresponding to the mode-coupling transition. The structural analysis reveals the emergence of icosahedral locally favoured structures, previously only found in trace quantities. We present a new approach to probe the shape of dynamically heterogeneous regions, which is insensitive to particle packing effects that can hamper such analysis. Our results indicate that the shape of the dynamically heterogeneous regions changes only weakly and moreover hint that the often-used four-point correlation length may exhibit a growth in excess of that which our method identifies. The growth of the size of the dynamically heterogeneous regions appears instead to be in line with the one of structural and dynamic propensity correlations.