Instantaneous normal modes of glass-forming liquids during the athermal relaxation process of the steepest descent algorithm

TL;DR

This study analyzes the instantaneous normal modes during the athermal relaxation of glass-forming liquids, revealing that long-time dynamics are driven by localized, flat directions in the potential energy landscape.

Contribution

It provides a detailed normal mode analysis during steepest descent relaxation, highlighting the role of localized, flat directions in glassy dynamics.

Findings

Dynamics driven by flat potential energy directions at long times

Localized modes dominate the relaxation process

Characterization of modes using landscape analysis methods

Abstract

Understanding glass formation by quenching remains a challenge in soft condensed matter physics. Recent numerical studies on steepest descent dynamics, which is one of the simplest models of quenching, revealed that quenched liquids undergo slow relaxation with a power law towards mechanical equilibrium and that the late stage of this process is governed by local rearrangements of particles. These advances motivate the detailed study of instantaneous normal modes during the relaxation process because the glassy dynamics is considered to be governed by stationary points of the potential energy landscape. Here, we performed a normal mode analysis of configurations during the steepest descent dynamics and found that the dynamics is driven by almost flat directions of the potential energy landscape at long times. These directions correspond to localized modes and we characterized them in terms of their statistics and structure using methods developed in the study of local minima of the potential energy landscape.