Density and bond-orientational relaxations in supercooled water |
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| Authors: | Jeremy C. Palmer Rakesh S. Singh Renjie Chen Fausto Martelli |
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| Affiliation: | 1. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USAjcpalmer@uh.edu;3. Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ, USA;4. Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX, USA;5. Department of Chemistry, Princeton University, Princeton, NJ, USA |
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| Abstract: | ![]()
ABSTRACTRecent 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. |
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| Keywords: | Liquid–liquid transition water models molecular simulation free energy |
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