Molecular Dynamics Simulation Of Water Limited In The Carbon Nanotube

CNTs has simple physical and chemical structure, but its geometric structure, and thecorresponding structure related to various physical and chemical properties are rich andcolorful. The considerable attention of scientists around the world has been draw by itsapplication in different fields.In the limited space of the different motion behavior of the fluid molecules each are notidentical due to confinement effect. Molecular dynamics simulation method was used to studyfluid behavior in nano-channels is a hot spot in recent years.In this paper, diffusion of water temperature of150k and300k type in different diameterarmchair CNTs was simulated and studied. Figures, about the radial distribution function andMSD (Mean Square Displacement) through the water at different temperatures and differentdiameter tubes in the diffusion process, were draw to reach the following conclusions:At the initial time, the diffusion behavior of water molecules in CNT is following the ballisticdiffusion mechanism, and it is also found in a common phenomenon in fluid of the free state.After a period of super diffusion mechanism and the diffusion mechanism (8,8) and (9,9),water molecules in CNT gradually transition to the Fickian diffusion mechanism, equates thediffusion mechanism of fluid in free state. Water molecules at (10,10) and above in CNTdirectly diffused to transition from the initial ballistic diffusion mechanism to the final Fickiandiffusion mechanism.That is to say, at the same temperature, the longer the tubes diameter, thecloser the water diffusion closes to bulk water; In CNT with the same diameter, with the change of the system temperature, diffusion coefficient has been changed. The higher thetemperature, the bigger diffusion coefficient would be.