Low-energy electronic properties of a pair of carbon nanotubes

A pair of carbon nanotubes, with the intertube interactions, are studied for the low-energy electronic properties within the tight-binding model. Energy dispersion, state degeneracy, subband spacing, energy gaps, and density of states are dominated by the nanotube radius and the relative azimuthal angle between two nanotubes. The intertube interactions could destroy double degeneracy. Moreover, they could effectively reduce energy gaps, or change narrow-gap systems into gapless systems. The above-mentioned electronic properties are strongly modulated by the transverse electric field. Such a field could induce new band-edge states.