Molecular dynamics simulation study for diffusion of Na+ ion in water-filled carbon nanotubes at 25°C

We present results of molecular dynamics simulations for diffusion of Na+ ion in water-filled carbon nanotubes (CNTs) at 25 degrees C using the extended simple point charge water potential. Simulation results indicate the general trend that the diffusion coefficients of Na+ ion and water molecule in CNTs decrease with an increase in water density and are larger than those in the bulk solution. The average potential energies of ion-water and water-water, the radial distribution functions, the hydration numbers and the residence times of the hydrated water molecules are discussed. The classical solventberg picture describes Na+ ion in water adequately for systems with the small values of diffusion coefficients.