Dynamical phase transitions in supercooled liquids: interpreting measurements of dynamical activity

TL;DR

This paper investigates dynamical phase transitions in supercooled liquids by comparing two activity measures, revealing their anti-correlation and scale-dependent coupling, which enhances understanding of structural relaxation and molecular motion.

Contribution

It introduces a comparative analysis of two activity measures in supercooled liquids and interprets their anti-correlation through scale-dependent coupling and energy landscape considerations.

Findings

Two activity measures are anti-correlated.

Different measures couple to different length and time scales.

Inactive states can have increased short-scale molecular motion.

Abstract

We study dynamical phase transitions in a model supercooled liquid. These transitions occur in ensembles of trajectories that are biased towards low (or high) dynamical activity. We compare two different measures of activity that were introduced in recent papers and we find that they are anti-correlated with each other. To interpret this result, we show that the two measures couple to motion on different length and time scales. We find that inactive states with very slow structural relaxation nevertheless have increased molecular motion on short scales. We discuss these results in terms of the potential energy landscape of the system and in terms of the liquid structure in active/inactive states.