Structure and Dynamics in Soft Systems on Approach to Jamming 

Amorphous, jammed systems of soft particles are found in a wide range of biological and industrial materials, including closely packed cells and soils. To understand their mechanical properties, such as yielding under external force, it is critical to first understand their structure and dynamics more fundamentally. While various studies explore the rearrangement dynamics and materials structure of these systems, the relationship between the two remains poorly understood. To study the influence of disordered structure on dynamics in soft systems approaching jamming, we model a binary mixture of 2D hard and soft particles under compression, with softness tuned through a repulsive isotropic pair potential. Glassy dynamics emerge at suitably high temperatures as the system is compressed and rearranges into a disordered state. Through a study of per-particle and system-scale measurements of structure and dynamics at various time scales, we explore the relationship of softness, amorphous structure, and dynamical heterogeneity. Different modes of motion, particularly strings of motion, emerge as drivers of glassy dynamics. Our findings give insight into the relationship between structure and dynamics in 2D amorphous materials, with applications for engineering their mechanical properties.