Single-parameter aging in a binary Lennard-Jones system

Area of Science:

• Condensed Matter Physics
• Computational Materials Science
• Statistical Mechanics

Background:

• Physical aging is a fundamental phenomenon in disordered materials, affecting their properties over time.
• Previous experimental studies validated a single-parameter aging scenario for small temperature jumps.
• The Kob-Andersen binary Lennard-Jones mixture is a model system for studying aging dynamics.

Purpose of the Study:

• To investigate physical aging in a 2:1 Kob-Andersen binary Lennard-Jones mixture using computer simulations.
• To test the applicability of the single-parameter aging scenario under large temperature variations.
• To monitor the time evolution of potential energy, virial, average squared force, and Laplacian of potential energy.

Main Methods:

• Utilized computer simulations of a 2:1 Kob-Andersen binary Lennard-Jones mixture.
• Initiated simulations from thermal-equilibrium states.
• Applied significant up and down temperature jumps to observe system response.

Main Results:

• All four monitored quantities (potential energy, virial, average squared force, Laplacian of potential energy) closely followed the single-parameter aging scenario.
• This aging behavior was observed despite the use of larger temperature jumps than in typical experiments.
• The relaxing parts of the monitored quantities were nearly identical across all temperature jumps, indicating a common material time.

Conclusions:

• The study confirms the validity of the single-parameter aging scenario for physical aging in this model system, even under large temperature perturbations.
• The findings suggest a robust aging mechanism characterized by a common material time across different physical quantities.
• This research provides valuable insights into the dynamics of disordered materials and validates simulation approaches for studying aging.