DISCLINATIONS OF MONOLAYER GRAPHITE AND THEIR ELECTRONIC STATES

The local density of states (LDOS) of a single disclination and a disclination pair of various configurations in the monolayer graphite is calculated by the recursion method introduced by Haydock [J. Phys. C 5, 2845 (1972)]. The LDOS shows the existence of some resonant states near the Fermi energy. At the Fermi level, the value of the LDOS vanishes for a single disclination of five- and seven-membered rings, and remains a finite value for four- and eight-membered rings. On going away from the disclination center, the shape of the LDOS approaches that of the perfect lattice. At the Fermi level, a sharp peak structure, which corresponds to a localized state, appears in the LDOS of fused disclinations consisting of a four-membered ring and a seven-membered ring, and the value of the LDOS vanishes in the case of fused disclinations consisting of two five-membered rings. But these features are drastically changed if the configuration of the disclination pair satisfies a certain simple condition. Using the fact that the Fermi level of these systems with disclinations is the same as that of the perfect monolayer graphite, the charge and the stability energy at each site are calculated from the LDOS. We show that the disclination center of a five-membered ring has a negative charge, that of a seven-membered ring has a positive charge, and that of an even membered ring is neutral.