Atomic scale sliding and rolling of carbon nanotubes

Using molecular statics and dynamics methods we investigate the motion of nanotubes on a graphite surface. Each nanotube has unique equilibrium orientations with sharp potential energy minima which lead to atomic scale locking of the nanotube. The effective contact area and the total interaction energy scale with the square root of the radius. Sliding and rolling nanotubes have different characters. The potential energy barriers for sliding nanotubes are higher than that for perfect rolling. When the nanotube is pushed, we observe a combination of atomic scale spinning and sliding motion