Issue 2, 2024

Origin of dielectric polarization suppression in confined water from first principles

Abstract

It has long been known that the dielectric constant of confined water should be different from that in bulk. Recent experiments have shown that it is vanishingly small, however the origin of the phenomenon remains unclear. Here we used ab initio molecular dynamics simulations (AIMD) and AIMD-trained machine-learning potentials to understand water's structure and electronic properties underpinning this effect. For the graphene and hexagonal boron-nitride substrates considered, we find that it originates in the spontaneous anti-parallel alignment of the water dipoles in the first two water layers near the solid interface. The interfacial layers exhibit net ferroelectric ordering, resulting in an overall anti-ferroelectric arrangement of confined water. Together with constrained hydrogen-bonding orientations, this leads to much reduced out-of-plane polarization. Furthermore, we directly contrast AIMD and simple classical force-field simulations, revealing important differences. This work offers insight into a property of water that is critical in modulating surface forces, the electric-double-layer formation and molecular solvation, and shows a way to compute it.

Graphical abstract: Origin of dielectric polarization suppression in confined water from first principles

Supplementary files

Article information

Article type
Edge Article
Submitted
07 sep 2023
Accepted
23 nov 2023
First published
04 dec 2023
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2024,15, 516-527

Origin of dielectric polarization suppression in confined water from first principles

T. Dufils, C. Schran, J. Chen, A. K. Geim, L. Fumagalli and A. Michaelides, Chem. Sci., 2024, 15, 516 DOI: 10.1039/D3SC04740G

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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