Non-Universality of Density and Disorder in Jammed Sphere Packings

TL;DR

This paper demonstrates that disordered jammed sphere packings in three dimensions can be generated across a wide density range using a new numerical method, challenging the idea of a universal jamming point based solely on density.

Contribution

The study introduces a novel numerical protocol to produce and tune collectively jammed packings over a broad density spectrum, showing the non-universality of the jamming density.

Findings

Packings generated with densities from 0.6 to approximately 0.74.

Packings exhibit variable disorder and are not confined to a single jamming density.

Results support the absence of a universal jamming point based on density.

Abstract

We show for the first time that collectively jammed disordered packings of three-dimensional monodisperse frictionless hard spheres can be produced and tuned using a novel numerical protocol with packing density $\phi$ as low as 0.6. This is well below the value of 0.64 associated with the maximally random jammed state and entirely unrelated to the ill-defined ``random loose packing'' state density. Specifically, collectively jammed packings are generated with a very narrow distribution centered at any density $\phi$ over a wide density range $\phi \in [0.6,~0.74048\ldots]$ with variable disorder. Our results support the view that there is no universal jamming point that is distinguishable based on the packing density and frequency of occurence. Our jammed packings are mapped onto a density-order-metric plane, which provides a broader characterization of packings than density alone. Other packing characteristics, such as the pair correlation function, average contact number and fraction of rattlers are quantified and discussed.