Role of Local Structure in the Enhanced Dynamics of Deformed Glasses

External stress can accelerate molecular mobility of amorphous solids by several orders of magnitude. The changes in mobility are commonly interpreted through the Eyring model, which invokes an empirical activation volume. Here, we analyze constant-stress molecular dynamics simulations and propose a structure-dependent Eyring model, connecting activation volume to a machine-learned field, softness. We show that stress has a heterogeneous effect on the mobility that depends on local structure through softness. The barrier impeding relaxation reduces more for well-packed particles, which explains the narrower distribution of relaxation time observed under stress.

Automated summary

External stress can greatly enhance the molecular mobility of amorphous solids, and this phenomenon can be explained by the Eyring model. In this study, we analyzed constant-stress molecular dynamics simulations and proposed a structure-dependent Eyring model that connects activation volume with a machine-learned field called softness. Our findings reveal that stress has a heterogeneous effect on mobility, which is determined by the local structure as described by softness.