Theoretical study of solid iron nanocrystal movement inside a carbon nanotube

We use a first-principles based kinetic Monte Carlo simulation to study the movement of a solid iron nanocrystal inside a carbon nanotube driven by the electrical current. The origin of the iron nanocrystal movement is the electromigration force. Even though the iron nanocrystal appears to be moving as a whole, we find that the core atoms of the nanocrystal are completely stationary, and only the surface atoms are moving. Movement in the contact region with the carbon nanotube is driven by electromigration forces, and the movement on the remaining surfaces is driven by diffusion. Results of our calculations also provide a simple model, which can predict the center of mass speed of the iron nanocrystal over a wide range of parameters. We find both qualitative and quantitative agreement of the iron nanocrystal center of mass speed with experimental data.