Structure of high-pressure supercooled and glassy water

TL;DR

This study uses numerical simulations to analyze the structure of supercooled and glassy water under high pressure, revealing continuous density changes and specific local hydrogen-bond geometries without first-order transitions.

Contribution

It introduces a novel topological analysis of the hydrogen-bond network to identify local geometries in high-pressure supercooled water.

Findings

Density increases continuously with pressure from 2.5 to 13 kbar.

No signs of first-order phase transitions observed.

Distinct local hydrogen-bond geometries identified.

Abstract

We numerically investigate the metastable equilibrium structure of deep supercooled and glassy water under pressure, covering the range of densities corresponding to the experimentally produced high-density and very-high-density amorphous phases. At $T = 188$ K, a continuous increase in density is observed on varying pressure from $2.5$ to $13$ kbar, with no signs of first-order transitions. Exploiting a recently proposed approach to the analysis of the radial distribution function -- based on topological properties of the hydrogen-bond network -- we are able to identify well-defined local geometries that involve pair of molecules separated by multiple hydrogen bonds, specific of the high and very high density structures.