How the Liquid-Liquid Transition Affects Hydrophobic Hydration in Deeply Supercooled Water

TL;DR

This study uses computer simulations to explore how the liquid-liquid transition in supercooled water influences hydrophobic hydration, revealing significant changes in solubility and thermodynamic signatures associated with structural transformations.

Contribution

It provides detailed phase diagram analysis and links the liquid-liquid transition to alterations in hydrophobic hydration properties in supercooled water.

Findings

Enhanced hydrophobic solubility in low density liquid

Minimum in hydration entropy and enthalpy during transition

Sign change in solvation heat capacity indicating altered hydration signatures

Abstract

We determine the phase diagram of liquid supercooled water by extensive computer simulations using the TIP5P-E model [J. Chem. Phys. {\bf 120}, 6085 (2004)]. We find that the transformation of water into a low density liquid in the supercooled range strongly enhances the solubility of hydrophobic particles. The transformation of water into a tetrahedrally structured liquid is accompanied by a minimum in the hydration entropy and enthalpy. The corresponding change in sign of the solvation heat capacity indicates a loss of one characteristic signature of hydrophobic hydration. The observed behavior is found to be qualitatively in accordance with the predictions of the information theory model of Garde et al. [Phys. Rev. Lett. {\bf 77}, 4966 (1996)].