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Two-Gaussian excitations model for the glass transition
Dmitry V Matyushov1, C A Angell
1Department of Chemistry and Biochemistry, Arizona State University, Tempe, 85287-1604, USA. dmitrym@asu.edu
The Journal of Chemical Physics
|August 6, 2005
Summary
This study introduces a modified two-state model for disordered systems, bridging simple models and the random energy model. It explains liquid thermodynamics and predicts phase transitions, resolving the Kauzmann paradox for fragile liquids.
Area of Science:
- Condensed Matter Physics
- Statistical Mechanics
- Physical Chemistry
Background:
- Disordered systems exhibit complex thermodynamic properties.
- Existing models like the random energy model (REM) have limitations in describing liquid behavior.
- Understanding the glass transition and Kauzmann paradox is crucial for materials science.
Purpose of the Study:
- Develop a modified two-state model incorporating Gaussian widths for site energies.
- Analyze thermodynamic properties in configuration space to bridge existing models.
- Investigate the behavior of fragile and strong liquids, including the Kauzmann singularity and glass transition.
Main Methods:
- Modified two-state model with Gaussian site energy distributions.
- Analysis of thermodynamic properties in configuration space.
- Comparison with simulations of binary mixtures and experimental data for laboratory systems.
Main Results:
- The model bridges simple two-state and random energy models.
- Kauzmann singularity is suppressed for stronger liquids.
- Reproduces heat capacity, excess entropy, and predicts first-order phase transitions for fragile liquids.
- Ideal glass state shows a narrow, invariant Gaussian width.
Conclusions:
- The model accurately reproduces experimental and simulation data for various liquids.
- Fragile liquids may resolve the Kauzmann paradox via a first-order transition.
- The temperature dependence of the energy landscape is key to liquid thermodynamics.