UNIVERSAL DENSITY-OF-STATES FOR CARBON NANOTUBES

=The density of states in the vicinity of the Fermi level of single-wa ll carbon nanotubes can be expressed in terms of a universal relations hip that depends only on whether the nanotube is metallic or semicondu cting. We compare the predictions of this approximate relationship wit h densities of states calculated using first-principles band structure results. These comparisons show that: this approximation works well f or energies within about 1 eV of the Fermi level. [S0031-9007(98)07 13 2-4].