Aging in a simple glassformer

TL;DR

This study uses molecular dynamics simulations to explore the aging process in a simple glassformer, revealing how the system approaches the mode-coupling critical surface and how its effective temperature evolves over time.

Contribution

It provides new insights into the out-of-equilibrium aging dynamics of glassformers, linking structural and vibrational properties to effective temperature during aging.

Findings

System remains close to the mode-coupling critical surface during aging.

Two-time correlation functions depend strongly on waiting time.

Energy of inherent structures defines a time-dependent effective temperature.

Abstract

Using molecular dynamics computer simulations we investigate the out-of-equilibrium dynamics of a Lennard-Jones system after a quench from a high temperature to one below the glass transition temperature. By studying the radial distribution function we give evidence that during the aging the system is very close to the critical surface of mode-coupling theory. Furthermore we show that two-time correlation functions show a strong dependence on the waiting time since the quench and that their shape is very different from the one in equilibrium. By investigating the temperature and time dependence of the frequency distribution of the normal modes we show that the energy of the inherent structures can be used to define an effective (time dependent) temperature of the aging system.