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Assessing thermodynamic-dynamic relationships for waterlike liquids
Margaret E Johnson1, Teresa Head-Gordon
1Department of Bioengineering, University of California, Berkeley, California 94720, USA.
The Journal of Chemical Physics
|June 11, 2009
Summary
Investigating waterlike liquids reveals that while Dzugutov scaling predicts diffusion anomalies, it fails at deep cooling. Dynamical heterogeneity emerges, requiring advanced structural correlations for predictive theories.
Area of Science:
- Condensed matter physics
- Computational chemistry
- Statistical mechanics
Background:
- Waterlike glass-forming liquids exhibit anomalous dynamics.
- Existing thermodynamic theories struggle to predict diffusion and viscosity trends.
Purpose of the Study:
- To rigorously evaluate entropic measures for predicting liquid dynamics.
- To investigate the predictive power of Adam-Gibbs and Dzugutov relations.
Main Methods:
- Simulated a family of isotropic potentials for waterlike liquids.
- Analyzed dynamics across various thermodynamic states.
- Evaluated entropic measures like configurational entropy (S(c)) and pair correlation approximations (S(2)).
Main Results:
- Adam-Gibbs relation poorly predicts fragility and density anomalies.
- Dzugutov scaling (S(2)) accurately describes diffusion anomalies in weakly supercooled states.
- Both methods deviate significantly at deeply supercooled temperatures.
Conclusions:
- Dynamical heterogeneity increases at low temperatures, showing non-Gaussian particle displacements.
- Predictive theories for liquid dynamics require higher structural correlations and complex connectivity paths.
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