Aging as dynamics in configuration space

TL;DR

This paper uses molecular dynamics simulations to explore aging in disordered systems, showing that aging can be understood through a decrease in effective configurational temperature, with faster equilibration near the mode-coupling critical temperature.

Contribution

It demonstrates that aging dynamics in a simple glass former can be described by a decreasing effective temperature, linking thermodynamics to out-of-equilibrium aging processes.

Findings

Aging correlates with a decrease in effective configurational temperature.

Faster equilibration occurs when quenched to the mode-coupling critical temperature.

Thermodynamic concepts effectively describe aging in disordered systems.

Abstract

The relaxation dynamics of many disordered systems, such as structural glasses, proteins, granular materials or spin glasses, is not completely frozen even at very low temperatures. This residual motion leads to a change of the properties of the material, a process commonly called aging. Despite recent advances in the theoretical description of such aging processes, the microscopic mechanisms leading to the aging dynamics are still a matter of dispute. In this Letter we investigate the aging dynamics of a simple glass former by means of molecular dynamics computer simulation. Using the concept of the inherent structure we give evidence that aging dynamics can be understood as a decrease of the effective configurational temperature T of the system. From our results we conclude that the equilibration process is faster when the system is quenched to T_c, the critical T of mode-coupling theory, and that thermodynamic concepts are useful to describe the out-of-equilibrium aging process.