With continuum-based density-functional theory, we have analyzed the liquid-crystal phases of finite-sized capped carbon nanotubes as a function of nanotube length and diameter for (i) the case when the nanotubes interact via the fully attractive van der Waals force; and (ii) when such interactions are screened out and the force is hard-core repulsive only. In the case of the former, we find that the columnar phase preempts all other phases at any reasonable temperature. This result is consistent with the formation of nanotube ropes during the high-temperature growth processes in laser vaporization and carbon arc experiments.

• Received 28 July 2000

DOI:https://doi.org/10.1103/PhysRevB.63.081403