title: Thermodynamic geometry, phase transitions, and the Widom line.
abstract: A microscopic characterization, based on the thermodynamic curvature R, is proposed for first-order liquid-gas phase transitions. Near the critical point, where R is proportional to the correlation volume ξ(3), we propose that R takes the same value in the coexisting phases. This proposal allows a determination of the liquid-gas coexistence curve with no use of the problematic Maxwell equal area construction. Furthermore, |R| ~ ξ(3) allows a direct determination of the Widom line in the supercritical regime. We illustrate with input from the van der Waals model and the National Institute of Standards and Technology Chemistry WebBook.
authors.affiliation: Division of Natural Sciences, New College of Florida, 5800 Bay Shore Road, Sarasota, Florida 34243-2109, USA. ruppeiner@ncf.edu
authors.forename: G
authors.initials: G
authors.lastname: Ruppeiner
authors.forename: A
authors.initials: A
authors.lastname: Sahay
authors.forename: T
authors.initials: T
authors.lastname: Sarkar
authors.forename: G
authors.initials: G
authors.lastname: Sengupta
mesh_terms: D003198:Computer Simulation; D005740:Gases / Q000737:chemistry*; D008956:Models, Chemical; D044367:Phase Transition; D012996:Solutions / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D005740:Gases; D012996:Solutions