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

Abstract

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 $\ensuremath{\lesssim}0.2 \mathrm{eV}$ and opens up a pseudogap of the same magnitude at ${E}_{F}.$ Soft librations at $\ensuremath{\nu}\ensuremath{\approx}12 {\mathrm{cm}}^{\ensuremath{-}1}$ 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 ${E}_{F}$ increases by 7% due to intertube coupling and by one order of magnitude due to K doping in ${\mathrm{KC}}_{8},$ these states do not couple to tube librations.