Potential energy landscape picture of zero-temperature avalanche criticality governing dynamics in supercooled liquids

TL;DR

This study uses molecular dynamics simulations to show that the slow dynamics in supercooled liquids can be explained by a zero-temperature avalanche criticality within the potential energy landscape framework.

Contribution

It introduces a potential-energy-landscape picture of avalanche criticality that unifies various observations in supercooled liquids near the mode-coupling transition.

Findings

Structural relaxation and dynamical heterogeneity are described by avalanche criticality.

Potential energy landscape analysis supports the avalanche picture.

The model explains saturation of dynamical susceptibility and localization of unstable modes.

Abstract

Supercooled liquids are metastable states realized by suppressing crystallization below the melting temperature. While it is well established that their dynamics slow down dramatically and become spatially heterogeneous upon cooling, the microscopic origin of these nontrivial glassy phenomena remains a matter of active debate. In the present study, by means of molecular dynamics simulations, we first demonstrate that nontrivial slow dynamics, such as structural relaxation and dynamical heterogeneity, can be consistently described within a zero-temperature avalanche criticality picture. Since this finding suggests that the potential energy landscape plays a crucial role in determining the dynamics, we further quantify the potential energy landscape from three distinct perspectives. Based on these analyses, we propose a potential-energy-landscape picture of avalanche criticality that is consistent with various previous studies. Our proposed picture explains in a unified manner previously unexplained observations near the mode-coupling transition, such as the saturation of the dynamical susceptibility and the localization of unstable modes in saddle configurations.