Conductance of nano-tube junctions and its scaling law

The conductance is calculated by Landauer’s formula with a simple tight binding model for junctions connecting two different metallic carbon nanotubes. These junctions are formed by a pair of disclinations, a 5-membered ring and a 7-membered ring, without dangling bonds. Conductances of about eight hundred kinds of junctions are obtained. The conductance is determined only by the ratio i/R where i is the distance between the two disclinations and R is the circumference of the thinner tube. When i/R ? 1, the conductance is found to be almost proportional to (i/R)^-3. Even when the Fermi energy is shifted by doping, an extended scaling law holds, so far as the channel number is kept two.