Free energy calculations and unbiased molecular dynamics targeting the liquid-liquid transition in water no man's land

J Chem Phys. 2023 Jan 7;158(1):014502. doi: 10.1063/5.0120789.

Abstract

The existence of a first-order phase transition between a low-density liquid (LDL) and a high-density liquid (HDL) form of supercooled water has been a central and highly debated issue of physics and chemistry for the last three decades. We present a computational study that allows us to determine the free-energy landscapes of supercooled water over a wide range of pressure and temperature conditions using the TIP4P/2005 force field. Our approach combines topology-based structural transformation coordinates, state-of-the-art free-energy calculation methods, and extensive unbiased molecular dynamics. All our diverse simulations cannot detect any barrier within the investigated timescales and system size, for a discontinuous transition between the LDL and HDL forms throughout the so-called "no man's land," until the onset of the solid, non-diffusive amorphous forms.

MeSH terms

  • Entropy
  • Molecular Dynamics Simulation*
  • Phase Transition
  • Temperature
  • Water* / chemistry

Substances

  • Water