Density and bond-orientational relaxations in supercooled water

Jeremy C. Palmer, Rakesh S. Singh, Renjie Chen, Fausto Martelli, Pablo G. Debenedetti

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)2580-2585
Number of pages6
JournalMolecular Physics
Issue number18
StatePublished - Sep 16 2016

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Molecular Biology
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry


  • Liquid–liquid transition
  • free energy
  • molecular simulation
  • water models


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