Random close packing of polydisperse hard spheres

TL;DR

This study investigates how compression speed affects the jamming density of polydisperse and monodisperse hard spheres, revealing that slower compression leads to higher jammed densities and linking out-of-equilibrium states to jamming points.

Contribution

It provides detailed data on how compression rate and polydispersity influence the jamming density of hard spheres, connecting out-of-equilibrium dynamics to jammed configurations.

Findings

Jammed density varies with compression rate and polydispersity.

Slower compression results in higher jammed densities.

Jamming density is determined by the out-of-equilibrium state at arrest.

Abstract

We study jammed configurations of hard spheres as a function of compression speed using an event-driven molecular dynamics algorithm. We find that during the compression, the pressure follows closely the metastable liquid branch until the system gets arrested into a glass state as the relaxation time exceeds the compression speed. Further compression yields a jammed configuration that can be regarded as the infinite pressure configuration of that glass state. Consequently, we find that the density of jammed packings varies from 0.638 to 0.658 for polydisperse hard spheres and from 0.635 to 0.645 for pure hard spheres upon decreasing the compression rate. This demonstrates that the density at which the systems falls out of equilibrium determines the density at which the system jams at infinite pressure. In addition, we give accurate data for the jamming density as a function of compression rate and size polydispersity.