Universität zu Köln

Mausbach, Peter, May, Helge-Otmar and Ruppeiner, George (2019). Thermodynamic metric geometry of the two-state ST2 model for supercooled water. J. Chem. Phys., 151 (6). MELVILLE: AMER INST PHYSICS. ISSN 1089-7690

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Abstract

Liquid water has anomalous liquid properties, such as its density maximum at 4 degrees C. An attempt at theoretical explanation proposes a liquid-liquid phase transition line in the supercooled liquid state, with coexisting low-density liquid (LDL) and high-density liquid (HDL) states. This line terminates at a critical point. It is assumed that the LDL state possesses mesoscopic tetrahedral structures that give it solidlike properties, while the HDL is a regular random liquid. But the short-lived nature of these solidlike structures makes them difficult to detect directly. We take a thermodynamic approach instead and calculate the thermodynamic Ricci curvature scalar R in the metastable liquid regime. It is believed that solidlike structures signal their presence thermodynamically by a positive sign for R, with a negative sign typically present in less organized fluid states. Using thermodynamic data from ST2 computer simulations fit to a mean field (MF) two state equation of state, we find significant regimes of positive R in the LDL state, supporting the proposal of solidlike structures in liquid water. In addition, we review the theory, compute critical exponents, demonstrate the large reach of the MF critical regime, and calculate the Widom line using R. Published under license by AIP Publishing.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Mausbach, Peter UNSPECIFIED UNSPECIFIED UNSPECIFIED May, Helge-Otmar UNSPECIFIED UNSPECIFIED UNSPECIFIED Ruppeiner, George UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-144338
DOI:	10.1063/1.5101075
Journal or Publication Title:	J. Chem. Phys.
Volume:	151
Number:	6
Date:	2019
Publisher:	AMER INST PHYSICS
Place of Publication:	MELVILLE
ISSN:	1089-7690
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LIQUID-LIQUID TRANSITION; RIEMANNIAN GEOMETRY; MOLECULAR-MODEL; CURVATURE; SINGULARITY; TIP4P/2005; NETWORKS; BEHAVIOR; ORDER Multiple languages Chemistry, Physical; Physics, Atomic, Molecular & Chemical Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/14433