Thermodynamics and Dynamics of a Monoatomic Glass-Former. Constant Pressure and Constant Volume Behavior
arXiv:0711.4283 · doi:10.1063/1.2883693
Abstract
We report constant-volume and constant-pressure simulations of the thermodynamic and dynamic properties of the low-temperature liquid and crystalline phases of the modified Stillinger-Weber (mSW) model. We have found an approximately linear increase of the effective Gaussian width of the distribution of inherent structures. This effect comes from non-Gaussianity of the landscape and is consistent with the predictions of the Gaussian excitations model representing the thermodynamics of the configurational manifold as an ensemble of excitations, each carrying an excitation entropy. The mSW model provides us with both the configurational and excess entropies, with the difference mostly attributed to vibrational anharmonicity. We therefore can address the distinction between the excess thermodynamic quantities often used in the Adam-Gibbs (AG) equation. We find a new break in the slope of the constant pressure AG plot when the excess entropy is used in the AG equation. The simulation diffusivity data are equally well fitted by applying a new equation, derived within the Gaussian excitations model, that emphasizes enthalpy over entropy as the thermodynamic control variable for transport in viscous liquids.
arXiv comment14 pages, 14 figures
References in corpus (22)
- Relation Between the Widom line and the Strong-Fragile Dynamic Crossover in Systems with a Liquid-Liquid Phase Transition
- Scaling behavior in the -relaxation regime of a supercooled Lennard-Jones mixture
- The relationship between fragility, configurational entropy and the potential energy landscape of glass forming liquids
- Inherent Structure Entropy of Supercooled Liquids
- Fragilities of Liquids Predicted from the Random First Order Transition Theory of Glasses
- Fragile-to-strong transition and polyamorphism in the energy landscape of liquid silica
- Configurational Entropy and Diffusivity of Supercooled Water
- Spatial correlations in the dynamics of glassforming liquids: Experimental determination of their temperature dependence
- The potential energy landscape of a model glass former: thermodynamics, anharmonicities, and finite size effects
- Theory of Aging in Structural Glasses
- Tuning of tetrahedrality in a silicon potential yields a series of monatomic (metal-like) glassformers of very high fragility
- The Glass Transition Temperature of Water: A Simulation Study
- Connection between Adam-Gibbs Theory and Spatially Heterogeneous Dynamics
- Free energy and configurational entropy of liquid silica: fragile-to-strong crossover and polyamorphism
- Dynamics and Configurational Entropy in the LW Model for Supercooled Orthoterphenyl
- Thermodynamic and structural aspects of the potential energy surface of simulated water
- Lennard-Jones binary mixture: a thermodynamical approach to glass transition
- Evaluation of configurational entropy of a model liquid from computer simulations
- Gaussian excitations model for glass-former dynamics and thermodynamics
- Two-Gaussian excitations model for the glass transition
- Non-Gaussian energy landscape of a simple model for strong network-forming liquids: accurate evaluation of the configurational entropy
- Model Energy Landscapes of Low-Temperature Fluids: Dipolar Hard Spheres