Density and bond-orientational relaxations in supercooled water. (16th September 2016)

• Record Type: Journal Article
• Authors: Palmer, Jeremy C.; Singh, Rakesh S.; Chen, Renjie; Martelli, Fausto; Debenedetti, Pablo G.
• Is Part Of: Molecular physics. Volume 114:Number 18(2016)
• Page Start: 2580
• Page End: 2585
• Publication Date: 2016-09-16
• Subjects: Liquid–liquid transition -- water models -- molecular simulation -- free energy; Molecules -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Molécules -- Périodiques; Chimie physique et théorique -- Périodiques; 539.6.05
• DOI: 10.1080/00268976.2016.1179351
• Languages: English
• ISSNs: 0026-8976

Abstract

ABSTRACT: Recent computational studies have reported evidence of a metastable liquid–liquid phase transition (LLPT) in molecular models of water under deeply supercooled conditions. A competing hypothesis suggests, however, that non-equilibrium artefacts associated with coarsening of the stable crystal phase have been mistaken for an LLPT in these models. Such artefacts are posited to arise due to a separation of time scales in which density fluctuations in the supercooled liquid relax orders of magnitude faster than those associated with bond-orientational order. Here, we use molecular simulation to investigate the relaxation of density and bond-orientational fluctuations in three molecular models of water (ST2, TIP5P and TIP4P/2005) in the vicinity of their reported LLPT. For each model, we find that density is the slowly relaxing variable under such conditions. We also observe similar behaviour in the coarse-grained mW model of water. Our findings, therefore, challenge the key physical assumption underlying the competing hypothesis. Abstract :