Effect of intertube coupling on the electronic structure of carbon nanotube ropes

We calculate the structural and electronic properties of an ordered ``bundle'' of (10,10) carbon nanotubes. Our results indicate that intertube coupling causes an additional band dispersion of 0.2 eV and opens up a pseudogap of the same magnitude at EF. Soft librations at ν≈12 cm^-1 are predicted to occur below the orientational melting temperature which marks the onset of tube rotations about their axis. Whereas the density of states near EF increases by 7% due to intertube coupling and by one order of magnitude due to K doping in KC₈, these states do not couple to tube librations.