Intermittent permeation of cylindrical nanopores by water

TL;DR

This study uses molecular dynamics simulations to explore how water permeates cylindrical nanopores, revealing that permeation is highly sensitive to pore radius and polarization, with intermittent flow and ion effects suggesting gating mechanisms.

Contribution

It demonstrates the impact of channel radius, polarization, and ions on water permeation, highlighting intermittent flow and contrasting behavior with Lennard-Jones fluids.

Findings

Permeation is intermittent at a threshold channel radius.

Presence of an ion inside the channel enhances permeation.

Confined water remains fluid and bulk-like, unlike Lennard-Jones fluids.

Abstract

Molecular Dynamics simulations of water molecules in nanometre sized cylindrical channels connecting two reservoirs show that the permeation of water is very sensitive to the channel radius and to electric polarization of the embedding material. At threshold, the permeation is {\emph{intermittent}} on a nanosecond timescale, and strongly enhanced by the presence of an ion inside the channel, providing a possible mechanism for gating. Confined water remains surprisingly fluid and bulk-like. Its behaviour differs strikingly from that of a reference Lennard-Jones fluid, which tends to contract into a highly layered structure inside the channel.