Numerical study of the lattice vacancy effects on the single-channel electron transport of graphite ribbons

Lattice vacancy effects on electrical conductance of nanographite ribbon are investigated by means of the Landauer approach using a tight binding model. In the low-energy regime ribbons with zigzag boundary provide a single conducting channel whose origin is connected with the presence of edge states. It is found that the chemical potential dependence of conductance strongly depends on the difference (Delta) of the number of removed A and B sublattice sites. The large lattice vacancy with Delta not equal 0 shows 2Delta zero-conductance dips in the single-channel region, however, the large lattice vacancy with Delta = 0 has no dip structure in this region. The connection between this conductance rule and the Longuet-Higgins conjecture is also discussed.