Density and bond-orientational relaxations in supercooled water
arXiv:1511.01959 · doi:10.1080/00268976.2016.1179351
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 artifacts associated with coarsening of the stable crystal phase have been mistaken for an LLPT in these models. Such artifacts 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 behavior in the coarse-grained mW model of water. Our findings therefore challenge the key physical assumption underlying the competing hypothesis.e find that density relaxes significantly faster than bond-orientational order, as incorrectly predicted by this competing hypothesis.
3 figures, included data for other models
References in corpus (6)
- How the Liquid-Liquid Transition Affects Hydrophobic Hydration in Deeply Supercooled Water
- Two-State Thermodynamics and the Possibility of a Liquid-Liquid Phase Transition in Supercooled TIP4P/2005 Water
- Free energy surface of ST2 water near the liquid-liquid phase transition
- Tuning the liquid-liquid transition by modulating the hydrogen bond angular flexibility in a model for water
- Time scales of supercooled water and implications for reversible polyamorphism
- Minimum in the thermal conductivity of supercooled water: a computer simulation study