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 less than or similar to 0.2 eV and opens up a pseudogap of the same magnitude at E-F. Soft librations at nu a pproximate to 12 cm(-1) are predicted to occur below the orientational melt ing temperature which marks the onset of tube rotations about their axis. W hereas the density of states near E-F increases by 7% due to intertube coup ling and by one order of magnitude due to K doping in KC8, these states do not couple to tube librations. [S0163-1829(98)52340-5].