Jeffrey R. Errington, University at Buffalo, Dept. of Chemical and Biological Engineering, 509 Furnas Hall, Buffalo, NY 14260, Thomas M. Truskett, Chemical Engineering and Institute for Theoretical Chemistry, The University of Texas at Austin, 1 University Station, C0400, Austin, TX 78712, and Jeetain Mittal, Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712.
Many thermodynamic and dynamic properties of water display anomalous behavior at low enough temperatures. In a recent study Yan et al. [1] identified a spherically-symmetric two-scale potential that displays many of the same anomalous properties as water. More specifically, for select parameterizations of the potential one finds that regions of structural, kinetic (increased diffusivity upon compression at constant temperature), and thermodynamic (fluid expansion upon isobaric cooling) anomalous behavior appear as nested domes in the temperature-density plane. These property relationships are similar to those found by Errington and Debenedetti [2] for a more realistic model of water. In this work we provide evidence that suggests that the anomalous regions specified above can all be linked through knowledge of the excess entropy. Specifically, we show how entropy scaling relationships developed by Rosenfeld [3] can be used to accurately predict the region of diffusivity anomalies, and propose where other anomalous kinetic regions fall for the Yan et al. model.
[1] Z. Yan, S. V. Buldyrev, N. Giovambattista, and H. E. Stanley, Phys. Rev. Lett. 95, 130604 (2005).
[2] J. R. Errington and P. G. Debenedetti, Nature 409, 318 (2001).
[3] Y. Rosenfeld, J. Phys.: Condens. Matter 11, 5415 (1999).