Ultra-high-density local structure of liquid water

TL;DR

This study uses all-atom simulations to analyze the local structure of liquid water, revealing a third ultra-high-density structure that influences water's anomalous properties and structural transitions.

Contribution

It identifies a previously unknown ultra-high-density local structure in liquid water and elucidates its role in stabilizing high-density configurations.

Findings

Discovery of a third ultra-high-density local structure.

This structure decreases the transition rate from high to low density.

It increases the reverse transition rate, stabilizing high-density water.

Abstract

The local structure of liquid water plays a key role in determining the anomalous properties of water. We run all-atom simulations for three microscopic water models, and use multiple order parameters to analyse the local structure of water. We identify three types of local structures. In addition to the well known low-density-liquid and high-density-liquid structures, the newly identified third type possesses an ultra high density and overcoordinated H-bonds. The existence of this third type decreases the rate of transition from the high-density-structure to low-density-structure and increases the rate of the reverse one, leading to the enhancement of the high-density-structure stability.