Metabasin dynamics and local structure in supercooled water

TL;DR

This study uses the Distance Matrix method to analyze metabasin dynamics in supercooled water, revealing how local structural rearrangements influence long-term relaxation processes.

Contribution

It introduces a novel application of the Distance Matrix method to characterize metabasin transitions and their role in the dynamics of supercooled water.

Findings

Metabasin transitions occur on timescales comparable to structural relaxation.

Rapid diffusional jumps involve groups of correlated particles forming compact clusters.

Mobile particles often have higher than four coordination, indicating distorted tetrahedral networks.

Abstract

We employ the Distance Matrix method to investigate metabasin dynamics in supercooled water. We find that the motion of the system consists in the exploration of a finite region of configuration space (enclosing several distinct local minima), named metabasin, followed by a sharp crossing to a different metabasin. The characteristic time between metabasin transitions is comparable to the structural relaxation time, suggesting that these transitions are relevant for the long time dynamics. The crossing between metabasins is accompanied by very rapid diffusional jumps of several groups of dynamically correlated particles. These particles form relatively compact clusters and act as cooperative relaxing units responsible for the density relaxation. We find that these mobile particles are often characterized by an average coordination larger than four, i.e. are located in regions where the tetrahedral hydrogen bond network is distorted.