Relevance of Shear Transformations in the Relaxation of Supercooled Liquids

TL;DR

This paper uses atomistic simulations to link local shear transformations with relaxation in supercooled liquids, revealing how residual plastic strengths predict heterogeneous dynamics and provide insights into the glass transition.

Contribution

It introduces a real-space method to connect local shear resistance with relaxation processes, highlighting the role of shear transformations in glassy dynamics.

Findings

Strong correlation between local residual plastic strengths and heterogeneous dynamics.

Maximum correlation occurs near the relaxation time at low temperatures.

Scaling between activation energy barriers and residual plastic strengths is established.

Abstract

While deeply supercooled liquids exhibit divergent viscosity and increasingly heterogeneous dynamics as the temperature drops, their structure shows only seemingly marginal changes. Understanding the nature of relaxation processes in this dramatic slowdown is key for understanding the glass transition. Here, we show by atomistic simulations that the heterogeneous dynamics of glass-forming liquids strongly correlate with the local residual plastic strengths along soft directions computed in the initial inherent structures. The correlation increases with decreasing temperature and is maximum in the vicinity of the relaxation time. For the lowest temperature investigated, this maximum is comparable with the best values from the literature dealing with the structure-property relationship. However, the nonlinear probe of the local shear resistance in soft directions provides here a real-space picture of relaxation processes. Our detection method of thermal rearrangements allows us to investigate the first passage time statistics and to study the scaling between the activation energy barriers and the residual plastic strengths. These results shed new light on the nature of relaxations of glassy systems by emphasizing the analogy between the thermal relaxations in viscous liquids and the plastic shear transformation in amorphous solids.