Relation between the Widom Line and the Dynamic Crossover in Systems with a Liquid-Liquid Phase Transition

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 102; no. 46; pp. 16558 - 16562
• Main Authors: Limei Xu, Kumar, Pradeep, Buldyrev, S. V., S. -H. Chen, P. H. Poole, F. Sciortino, Stanley, H. E.
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 15.11.2005; National Acad Sciences
• Subjects: Biological Sciences; Contour lines; Critical points; Crossovers; High temperature; Liquids; Low temperature; Mathematical maxima; Phase diagrams; Phase transitions; Physical Sciences; Power laws; Thermodynamics
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0507870102

We investigate, for two water models displaying a liquid-liquid critical point, the relation between changes in dynamic and ther-modynamic anomalies arising from the presence of the liquid-liquid critical point. We find a correlation between the dynamic crossover and the locus of specific heat maxima$C_{P}^{max}$("Widom line") emanating from the critical point. Our findings are consistent with a possible relation between the previously hypothesized liquid-liquid phase transition and the transition in the dynamics recently observed in neutron scattering experiments on confined water. More generally, we argue that this connection between$C_{P}^{max}$and dynamic crossover is not limited to the case of water, a hydrogen bond network-forming liquid, but is a more general feature of crossing the Widom line. Specifically, we also study the Jagla potential, a spherically symmetric two-scale potential known to possess a liquid-liquid critical point, in which the competition between two liquid structures is generated by repulsive and attractive ramp interactions.