Coarse Nonlinear Dynamics and Metastability of Filling-Emptying Transitions: Water in Carbon Nanotubes

TL;DR

This paper investigates the nonlinear dynamics and metastability of water filling and emptying carbon nanotubes using a coarse-grained MD approach, revealing how pore hydrophobicity influences state stability and hysteresis.

Contribution

It introduces a coarse-grained MD method to analyze water dynamics in nanotubes, linking microscopic simulations with continuum bifurcation analysis to understand metastability.

Findings

Water in nanotubes exhibits metastable filled and empty states.

Hydrophobicity controls the transition dynamics and hysteresis.

The approach links MD simulations with bifurcation analysis.

Abstract

Using a Coarse-grained Molecular Dynamics (CMD) approach we study the apparent nonlinear dynamics of water molecules filling/emptying carbon nanotubes as a function of system parameters. Different levels of the pore hydrophobicity give rise to tubes that are empty, water-filled, or fluctuate between these two long-lived metastable states. The corresponding coarse-grained free energy surfaces and their hysteretic parameter dependence are explored by linking MD to continuum fixed point and bifurcation algorithms. The results are validated through equilibrium MD simulations.