Cavity-water interface is polar

TL;DR

This study uses numerical simulations to analyze the electrostatic properties of water molecules around cavities, revealing enhanced local dielectric response and linear electrostatic behavior that aligns with continuum models as cavity size increases.

Contribution

It provides new insights into the dielectric response and electrostatic behavior of water at cavity interfaces, highlighting size-dependent effects and the applicability of continuum electrostatics.

Findings

Dielectric constant peaks increase with cavity size.

Polar hydration shells extend into bulk water up to the cavity radius.

Electrostatic fields follow linear response and match continuum predictions for larger cavities.

Abstract

We present the results of numerical simulations of the electrostatics and dynamics of water hydration shells surrounding Kihara cavities given by a Lennard-Jones (LJ) layer at the surface of a hard-sphere cavity. The local dielectric response of the hydration layer substantially exceeds that of bulk water, with the magnitude of the dielectric constant peak in the shell increasing with the growing cavity size. The polar shell propagates into bulk water to approximately the cavity radius. The statistics of the electrostatic field produced by water inside the cavity follow linear response and approach the prediction of continuum electrostatics with increasing cavity size.