The structural origin of the hard-sphere glass transition in granular packing

TL;DR

This paper demonstrates that the glass transition in granular packing, modeled as hard spheres, is a thermodynamic phase transition linked to a hidden polytetrahedral order that correlates with slow dynamics.

Contribution

It reveals a thermodynamic origin of the glass transition in granular packing and identifies a specific static structural order associated with dynamic arrest.

Findings

Polytetrahedral order correlates with slow dynamics.

Glass transition follows an entropy-driven nucleation process.

Identifies a structural glass order in hard-sphere glasses.

Abstract

Glass transition is accompanied by a rapid growth of the structural relaxation time and a concomitant decrease of configurational entropy. It remains unclear whether the transition has a thermodynamic origin, and whether the dynamic arrest is associated with the growth of a certain static order. Using granular packing as a model hard-sphere glass, we show the glass transition as a thermodynamic phase transition with a "hidden" polytetrahedral order. This polytetrahedral order is spatially correlated with the slow dynamics. It is geometrically frustrated and has a peculiar fractal dimension. Additionally, as the packing fraction increases, its growth follows an entropy-driven nucleation process, similar to that of the random first-order transition theory. Our study essentially identifies a long-sought-after structural glass order in hard-sphere glasses.