The effects of impurities and local structural defects upon metallic nanotubes were calculated by using an ab initio pseudopotential method, within the Landauer formalism. It was noted that substitutionally doped B or N produced quasi-bound impurity states of definite parity, and reduced the conductance by one quantum unit (2e2/h) via resonant back-scattering. The resonant states exhibited a strong similarity to acceptor or donor states in semiconductors. The Stone-Wales defect also produced quasi-bound states, and exhibited a quantized conductance reduction. In the case of a vacancy, the conductance exhibited a much more complex behavior than did the widely-used π-electron tight-binding model.

Defects, Quasi-Bound States and Quantum Conductance in Metallic Carbon Nanotubes. H.J.Choi, J.Ihm, S.G.Louie, M.L.Cohen: Physical Review Letters, 2000, 84[13], 2917-20