Relaxation pathway confinement in glassy dynamics

TL;DR

This paper investigates how, in supercooled glass-forming systems, the pathways for particle relaxation become increasingly confined, revealing an entropic funnel that limits the mobility routes as the system cools.

Contribution

It introduces a novel measure of mobility excess over propensity to demonstrate pathway confinement in glassy dynamics during supercooling.

Findings

Increasing confinement of relaxation pathways with supercooling

Decay and collapse of Shannon entropy indicating pathway restriction

Evidence of an entropic funnel limiting particle mobility

Abstract

We compute for an archetypical glass-forming system the excess of particle mobility distributions over the corresponding distribution of dynamic propensity, a quantity that measures the tendency of the particles to be mobile and reflects the local structural constraints. This enables us to demonstrate that, on supercooling, the dynamical trajectory in search for a relaxation event must deal with an increasing confinement of relaxation pathways. This ``entropic funnel'' of relaxation pathways built upon a restricted set of mobile particles is also made evident from the decay and further collapse of the associated Shannon entropy.