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Large temperature-up-jump simulations of a binary Lennard-Jones system
Aude Y Amari1, Lorenzo Costigliola1, Jeppe C Dyre1
1Roskilde University, Glass and Time, IMFUFA, Department of Science and Environment, P.O. Box 260, DK-4000 Roskilde, Denmark.
Physical Review. E
|May 16, 2026
Summary
This study simulates physical aging in a binary liquid after large temperature changes. The Tool-Narayanaswamy material-time concept shows better aging prediction for smaller temperature jumps, confirming it works best for systems near equilibrium.
Area of Science:
- Condensed Matter Physics
- Computational Materials Science
- Soft Matter Physics
Background:
- Physical aging is a fundamental process in disordered materials, affecting their properties over time.
- The Tool-Narayanaswamy (TN) model provides a framework to describe aging using a material time concept.
- Understanding aging is crucial for predicting the long-term behavior of glasses and complex liquids.
Purpose of the Study:
- To investigate the applicability of the Tool-Narayanaswamy (TN) material-time concept to extreme physical aging scenarios in a binary liquid.
- To assess how well the TN model predicts the relaxation of various dynamic quantities after large temperature up jumps.
- To determine the limitations of the TN aging formalism for systems significantly perturbed from equilibrium.
Main Methods:
- Simulations of a binary Kob-Andersen-type Lennard-Jones liquid.
- Implementing large temperature up jumps from equilibrated states.
- Monitoring potential energy, self-intermediate scattering function, mean-square displacement, dynamic susceptibility (χ₄), and non-Gaussian parameter (α₂).
- Defining and utilizing a potential-energy-based material time (ξ).
Main Results:
- The triangular relation of potential energy is well obeyed, enabling the definition of a material time (ξ).
- The TN material-time prediction of autocorrelation function collapse is more accurate for smaller temperature jumps (0.43→0.48) than for larger ones (0.37→0.48).
- The TN aging formalism's effectiveness diminishes as the system moves further from equilibrium.
Conclusions:
- The TN material-time concept is generally applicable but performs best for systems close to equilibrium.
- Further research is needed to explore if individual material times for each aging quantity or a generalized local material time can improve collapse.
- The study highlights the importance of system proximity to equilibrium for the validity of TN aging predictions.
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