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 $\lesssim 0.2\hspace{0.5em}\mathrm{eV}$ and opens up a pseudogap of the same magnitude at $E_F.$ Soft librations at $\nu \approx 12\hspace{0.5em}{\mathrm{cm}}^{-1}$ 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 $E_F$ 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.

• Received 20 April 1998

DOI:https://doi.org/10.1103/PhysRevB.58.R13314