Conductance spectra of metallic carbon nanotube bundles from first principles

We report a first-principles analysis of electronic transport characteristics for (n,n) carbon nanotube bundles. When n is not a multiple of 3, intertube coupling causes universal conductance suppression near Fermi level regardless of the rotational arrangement of individual tubes. However, when n is a multiple of 3, the bundles exhibit a diversified conductance dependence on the orientation details of the constituent tubes. The total energy of the bundle is also sensitive to the orientation arrangement only when n is a multiple of 3. All the transport properties and band structures can be well understood from the symmetry consideration of whether the rotational symmetry of the individual tubes is commensurate with that of the bundle. This finding may shed some light on understanding and applications of nanotube bundle interconnect technology.