Predicting the effective temperature of a glass

Area of Science:

• Condensed Matter Physics
• Statistical Mechanics
• Computational Physics

Background:

• The effective temperature of glasses is a crucial parameter in understanding their properties.
• Previous work by Di Leonardo et al. suggested this temperature depends on the final density after a quench.
• The universality of this finding across different liquids was not fully established.

Purpose of the Study:

• To investigate whether the effective temperature of a glass depends only on the final density, irrespective of the quench protocol.
• To determine if this property is specific to the Lennard-Jones liquid or applicable to other strongly correlating liquids.
• To validate the predictive power of a single quench simulation for glass effective temperatures.

Main Methods:

• Molecular dynamics simulations were performed.
• The Kob-Andersen binary Lennard-Jones liquid was simulated to test the hypothesis.
• The monatomic Lennard-Jones Gaussian liquid was simulated to assess the limits of the finding.

Main Results:

• The effective temperature of Lennard-Jones glasses was found to depend only on the final density, confirming Di Leonardo et al.'s findings.
• This density-dependent effective temperature was observed to be a general feature of strongly correlating liquids.
• Simulations of the Kob-Andersen liquid validated that data from a single quench predicts the effective temperature.
• The prediction did not hold for the nonstrongly correlating monatomic Lennard-Jones Gaussian liquid.

Conclusions:

• The effective temperature of glasses formed from strongly correlating liquids is determined solely by the final density.
• A single quench simulation provides sufficient data to predict the effective temperature for any glass produced by jumping from an equilibrium state in these liquids.
• This principle does not apply to nonstrongly correlating liquids, highlighting the importance of liquid dynamics.