Diffusive motion of C60 on a graphene sheet

The motion of a C-60 molecule over a graphene sheet at finite temperature is investigated both theoretically and computationally. We show that a graphene sheet generates a van der Waals laterally periodic potential, which directly influences the motion of external objects in its proximity. The translational motion of a C-60 molecule near a graphene sheet is found to be diffusive in the lateral directions, while in the perpendicular direction, the motion may be described as diffusion in an effective harmonic potential which is determined from the distribution function of the position of the C-60 molecule. We also examine the rotational diffusion of C-60 and show that its motion over the graphene sheet is not a rolling motion.