Small crystal approach for the electronic properties of double-wall carbon nanotubes

A small crystal approach (SCA) is a real-space approach that allows one to introduce local symmetry breaking which is difficult to consider in a reciprocal space approach. We apply the SCA to the case of double-wall nanotubes, for which the effects of the orientation-dependent intertube interactions have to be taken into account. The results suggest a solution for the usual difficulties in assigning the resonance Raman spectra of double-wall nanotubes since important variations of the electronic spectra of these carbon nanotubes are found with respect to those of the constituent single-wall nanotubes.