Single-parameter aging in a binary Lennard-Jones system

TL;DR

This study uses computer simulations to demonstrate that a binary Lennard-Jones system exhibits single-parameter aging behavior across various quantities following temperature jumps, confirming the robustness of this aging model.

Contribution

It provides evidence that single-parameter aging applies to a binary Lennard-Jones mixture with large temperature jumps, extending previous experimental findings.

Findings

All monitored quantities follow single-parameter aging after temperature jumps.

Relaxation parts are nearly identical across different quantities and temperature jumps.

The results validate the single-parameter-aging scenario for larger temperature changes.

Abstract

This paper studies physical aging by computer simulations of a 2:1 Kob-Andersen binary Lennard-Jones mixture, a system that is less prone to crystallization than the standard 4:1 composition. Starting from thermal-equilibrium states, the time evolution of the following four quantities is monitored following up and down jumps in temperature: the potential energy, the virial, the average squared force, and the Laplacian of the potential energy. Despite the fact that significantly larger temperature jumps are studied here than in previous experiments, to a good approximation all four quantities conform to the single-parameter-aging scenario derived and validated for small jumps in experiments [Hecksher et al., J. Chem. Phys. 142, 241103 (2015)]. As a further confirmation of single-parameter aging with a common material time for the different quantities monitored, their relaxing parts are found to be almost identical for all temperature jumps.