Abstract
ABSTRACTWe report a numerical test of the Adam–Gibbs relation for the TIP4P/2005 model of water. The configurational entropy is here evaluated as the logarithm of the number of different basins in the potential energy landscape sampled in equilibrium conditions. Despite the non-monotonic behaviour which characterise the density dependence of the diffusion coefficient, the Adam–Gibbs relation is satisfied within the numerical precision in a wide range of densities and temperatures. We also show that expressions based on the excess entropy (the logarithm of the number of sampled microstates in phase space) fail in the region of densities where a tetrahedral hydrogen bond network develops.
Highlights
One of the most intriguing phenomena in condensed matter physics is the glass transition
We report a numerical test of the Adam–Gibbs relation for the TIP4P/2005 model of water
Very recently we have reported a numerical study of the statistical properties of the potential energy landscape (PEL) for the TIP4P/2005 model of water [28]
Summary
One of the most intriguing phenomena in condensed matter physics is the glass transition. Protein solutions typically form disordered arrested states readily [1], making crystallisation the hard problem [2] Others such as silica are both fairly obtained as a crystalline solid or as a glass [3]. We have shown that a Gaussian PEL properly describes the simulation data, reproducing the thermodynamic anomalies characteristic of water and predicting the existence of a liquid-liquid critical point. In this contribution we expand the landscape analysis to dynamics, testing the validity of the Adam–Gibbs relation for TIP4P/2005, the most accurate classical water model to date [29,30]. We compare the T and density (ρ) dependence of the diffusion coefficient with other propositions relating the excess Sexc and the two-point entropy with dynamics [31]
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