Diffusion and drift of a graphene flake on a graphite surface were analyzed. A potential energy relief for the flake was computed using ab initio and empirical calculations. Based upon an analysis of this relief, a mechanism for diffusion and drift of the flake was proposed. According to the proposed mechanism, rotational transition of the flake from an commensurate to incommensurate state took place with subsequent simultaneous rotation and translational motion until a commensurate state was reached again, and so on. Analytical expressions for the diffusion coefficient and mobility of the flake, corresponding to different mechanisms, were derived for wide ranges of temperature and flake size. The simulations demonstrated that the proposed mechanism could predominate under certain conditions.

Diffusion and Drift of Graphene Flake on Graphite Surface. Irina V. Lebedeva, I.V., Knizhnik, A.A., Popov, A.M., Ershova, O.V., Lozovik, Y.E., Potapkin, B.V.: Journal of Chemical Physics, 2011, 134, 104505