The effect of polymorphism on the structural, dynamic and dielectric properties of plastic crystal water: A molecular dynamics simulation perspective

TL;DR

This study uses molecular dynamics simulations to explore how different polymorphs of plastic crystal water exhibit distinct structural, dynamic, and dielectric behaviors, revealing heterogeneities and hindered rotations.

Contribution

It provides new insights into the local structural and dynamical heterogeneities of water polymorphs using advanced simulation techniques.

Findings

Significant differences in local orientational structure between polymorphs

Hindered molecular rotation more pronounced in body-centered-cubic phase

Distinct dielectric properties due to dipolar correlation differences

Abstract

We have employed molecular dynamics simulations based on the TIP4P/2005 water model to investigate the local structural, dynamical, and dielectric properties of the two recently reported body-centered-cubic and face-centered-cubic plastic crystal phases of water. Our results reveal significant differences in the local orientational structure and rotational dynamics of water molecules for the two polymorphs. The probability distributions of trigonal and tetrahedral order parameters exhibit a multi-modal structure, implying the existence of significant local orientational heterogeneities, particularly in the face-centered-cubic phase. The calculated hydrogen bond statistics and dynamics provide further indications of the existence of a strongly heterogeneous and rapidly interconverting local orientational structural network in both polymorphs. We have observed a hindered molecular rotation, much more pronounced in the body-centered-cubic phase, which is reflected by the decay of the fourth-order Legendre reorientational correlation functions and angular Van Hove functions. Molecular rotation, however, is additionally hindered in the high-pressure liquid compared to the plastic crystal phase. The results obtained also reveal significant differences in the dielectric properties of the polymorphs due to the different dipolar orientational correlation characterizing each phase.