Conductance quantization in the presence of huge and short-range potential in carbon nanotubes

Conductance of carbon nanotubes (CNs) with a pair of impurities having a huge and short-range potential is studied within a tight-binding model. When a pair occupies different sublattices, the conductance is given by 2e(2)/pi h same as in ideal CNs for a small distance and approaches either e(2)/pi h or 0 with the increase of the distance depending on types of their sites. When a pair occupies same sublattice points, the conductance is either e(2)/pi h or 0 independent of the distance. (C) 2000 Elsevier Science B.V. All rights reserved.