Liquid state of hydrogen bond network in ice

TL;DR

This paper investigates a temperature-induced phase transition in ice where the hydrogen bond network melts while the oxygen lattice remains largely intact, revealing a liquid-like state of hydrogen bonds.

Contribution

It introduces a new understanding of hydrogen bond network melting in ice driven by Coulomb interactions and violations of Bernal-Fowler rules.

Findings

Step-wise increase in violations by 6-7 orders of magnitude.

First-order phase transition with decreased relaxation time.

Approximately 7% of hydrogen bonds are broken after melting.

Abstract

Here we show that the Coulomb interaction between violations of the Bernal-Fowler rules leads to a temperature induced step-wise increase in their concentration by 6-7 orders of magnitude. This first-order phase transition is accompanied by commensurable decrease in the relaxation time and can be interpreted as melting of the hydrogen bond network. The new phase with the melted hydrogen lattice and survived oxygen one is unstable in the bulk of ice, and further drastic increase in the concentrations of oxygen interstitials and vacancies accomplishes the ice melting. The fraction of broken hydrogen bonds immediately after the melting is about 0.07 of their total number that implies an essential conservation of oxygen lattice in water.