Chirality Dependence of Exciton Energies in Double-Wall Carbon Nanotubes

Exciton energies in double-wall carbon nanotubes are theoretically studied based on an effective-mass approximation. Effects of tube chirality responsible for family pattern of the exciton energies are included as higher-order corrections describing trigonal warping, curvature, and lattice distortion. The redshift of the exciton energy due to interwall screening exhibits a family pattern with small energy spread. The shift and its family spread of the inner tube are almost determined by the interwall distance and by whether the outer tube is semiconducting or metallic regardless of the detailed structure.