Jammed Particle Configurations and Dynamics in High-Density Lennard-Jones Binary Mixtures in Two Dimensions

TL;DR

This study investigates how particle configurations and dynamics in dense Lennard-Jones binary mixtures evolve with composition, revealing diverse structures and heterogeneous, localized deformation behaviors in jammed states and under shear.

Contribution

It provides new insights into the structural transitions and dynamic heterogeneity in high-density binary mixtures, especially the formation of crystalline, polycrystalline, and glassy states.

Findings

Configurations include crystalline, polycrystalline, and glassy states.

Dynamics are highly heterogeneous and slow in jammed states.

Shear induces localized shear bands with finite lifetimes.

Abstract

We examine the changeover in the particle configurations and the dynamics in dense Lennard-Jones binary mixtures composed of small and large particles. By varying the composition at a low temperature, we realize crystal with defects, polycrystal with small grains, and glass with various degrees of disorder. In particular, we show configurations where small crystalline regions composed of the majority species are enclosed by percolated amorphous layers composed of the two species. We visualize the dynamics of configuration changes using the method of bond breakage and following the particle displacements. In quiescent jammed states, the dynamics is severely slowed down and is highly heterogeneous at any compositions. In shear, plastic deformations multiply occur in relatively fragile regions, growing into large-scale shear bands where the strain is highly localized. Such bands appear on short time scales and change on long time scales with finite life times.