Modulation of intertube band dispersion relation of carbon nanotube bundles by symmetry and intertube wave function coupling

Abstract

Based on density functional theory with a local density approximation and the simple tight-binding approximation, we investigated an electronic structure of carbon nanotube bundles in terms of mutual nanotube arrangement. The dispersion relation near the Fermi level along the intertube direction was found to be sensitive to the nanotube species and their mutual orientation within the bundles. Nanotube bundles with three-fold symmetry exhibited a substantial orientation dependence in the band dispersion relation along the intertube direction. The tight-binding calculation and wave function analysis revealed that this orientation dependence arises from the intertube wave function coupling and whether a node exists between nanotubes.