SIMPLE-MODEL OF SURFACE SUPERLATTICES ON GRAPHITE

The discrete Laplace equation on a honeycomb lattice, perturbed by a p oint potential, is considered as a simple model of single-ion impact o n a graphite surface. The asymptotic behavior of the perturbation of t he local surface density of electron states is analyzed. It is shown t hat this perturbation is equal to the experimentally observed superlat tice. It is then established that the main purpose of the existence of such superlattices is that of unconnectedness of the isoenergetic cur ve of the Brillouin zone.