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Numerical test of the Edwards conjecture shows that all packings are equally probable at jamming

Accepted version
Peer-reviewed

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Article

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Authors

Martiniani, Stefano  ORCID logo  https://orcid.org/0000-0003-2028-2175
Schrenk, KJ 
Ramola, K 
Chakraborty, B 

Abstract

In the late 1980s, Sam Edwards proposed a possible statistical-mechanical framework to describe the properties of disordered granular materials1. A key assumption underlying the theory was that all jammed packings are equally likely. In the intervening years it has never been possible to test this bold hypothesis directly. Here we present simulations that provide direct evidence that at the unjamming point, all packings of soft repulsive particles are equally likely, even though generically, jammed packings are not. Typically, jammed granular systems are observed precisely at the unjamming point since grains are not very compressible. Our results therefore support Edwards’ original conjecture. We also present evidence that at unjamming the configurational entropy of the system is maximal.

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Keywords

computational science, soft materials, statistical physics, thermodynamics and nonlinear dynamics

Journal Title

Nature Physics

Conference Name

Journal ISSN

1745-2473
1745-2481

Volume Title

13

Publisher

Springer Nature
Sponsorship
Engineering and Physical Sciences Research Council (EP/I001352/1)
Engineering and Physical Sciences Research Council (EP/I000844/1)
S.M. acknowledges financial support by the Gates Cambridge Scholarship. K.J.S. acknowledges support by the Swiss National Science Foundation under Grant No. P2EZP2-152188 and No. P300P2-161078. D.F. acknowledges support by EPSRC Programme Grant EP/I001352/1 and EPSRC grant EP/I000844/1. K.R. and B.C. acknowledge the support of NSF-DMR 1409093 and the W. M. Keck Foundation.