Electronic structure of a stepped graphite surface

Abstract

A first-principles band calculation and theoretical simulation of scanning tunneling microscopy and spectroscopy (STM and STS) are performed on a stepped surface of graphite. The calculated band structure and the density of states are similar to those of fullerene tubules. Unlike in fullerene tubules, however, a localized state on the step appears at the Fermi level due to the existence of an edge in the graphite sheet. The calculated STM image shows a triangular lattice structure similar to that of the bulk graphite. However, the positions of the peaks of the tunneling current do not coincide with the atomic sites and shift gradually as they diverge from the step. The calculated STS spectra at a location near the step show a strong peak reflecting the localized state.