Equilibrium sampling of hard spheres up to the jamming density and beyond

TL;DR

This paper introduces an optimized particle-swap Monte Carlo method that efficiently equilibrates polydisperse hard spheres up to and beyond the jamming density, revealing new insights into the nature of the jamming transition.

Contribution

The authors develop and optimize a particle-swap Monte Carlo algorithm capable of equilibrating systems at densities previously inaccessible, challenging existing theories about the jamming transition.

Findings

No glass singularity occurs before the jamming density.

Equilibrium fluid and jammed states can share the same density.

The jamming transition is not the endpoint of the fluid phase.

Abstract

We implement and optimize a particle-swap Monte-Carlo algorithm that allows us to thermalize a polydisperse system of hard spheres up to unprecedentedly-large volume fractions, where \revise{previous} algorithms and experiments fail to equilibrate. We show that no glass singularity intervenes before the jamming density, which we independently determine through two distinct non-equilibrium protocols. We demonstrate that equilibrium fluid and non-equilibrium jammed states can have the same density, showing that the jamming transition cannot be the end-point of the fluid branch.