## Random jammed packings: from structure to elasticity

#### by Prof. Alessio Zaccone

*Department of Physics "A. Pontremoli", University of Milan*

##### at Biological and soft-matter physics

Thu, 04 May 2023, 14:10

Sacta-Rashi Building for Physics (54), room 207: ***NOTE CHANGE OF TIME - 14:10***

#### Abstract

The statistical physics of hard sphere systems has been one of the most successful applications of modern statistical mechanics, with milestone results developed in the 20th century and early 21st century by, among others, Percus, Lebowitz, Stillinger and Torquato, Edwards, Parisi and others. Inspired by this tradition of successes in predicting the equilibrium-like properties of hard-sphere systems, I will show how an analytical closed-form solution for the random close packing volume fractions in d=2 and d=3 can be built from the Percus-Yevick solution to the many-body hard sphere hierarchy in the liquid state [1]. A justification to the assumptions used (i.e. 1-the use of liquid state theory at jamming, and, 2-the use of the ordered close packing FCC condition as an effective boundary condition) has been provided in [2] based on new numerical calculations with the Jiao-Torquato algorithm. I will then show how the analytical solution can be extended to make predictions of RCP volume fractions for polydisperse and bidisperse hard sphere systems [2] as a function of the size polydispersity (for binary mixtures, mixture composition and the size asymmetry), in good agreement with numerical simulations with no adjustable parameters. Finally, I will present closed-form results for the elasticity of random sphere packings [3] and recent developments for the plasticity of amorphous solids, where unexpected topological defects have been recently discovered [4].

[1] A. Zaccone, Phys. Rev. Lett. 128, 028002 (2022)

[2] C. Anzivino et al., J. Chem. Phys. 158, 044901 (2023)

[3] A. Zaccone & E. Scossa-Romano, Phys. Rev. B 83, 184205 (2011)

[4] M. Baggioli et al., Phys. Rev. Lett. 127, 015501 (2021)

Created on 28-04-2023 by Granek, Rony (rgranek)

Updaded on 03-05-2023 by Granek, Rony (rgranek)