Tight-binding calculations, using a two-dimensional model of the graphite lattice, lead to a point of contact of valence and conduction bands at the corner of the reduced Brillouin zone. A perturbation calculation which starts with wave functions of the two-dimensional lattice and is applied to the three-dimensional lattice is described. Some general features of the structure of the $\pi$ bands in the neighborhood of the zone edge are obtained and are expressed in terms of appropriate parameters.

• Received 13 August 1957

DOI:https://doi.org/10.1103/PhysRev.109.272