With continuum-based density-functional theory, we have analyzed the liquid
-crystal phases of finite-sized capped carbon nanotubes as a function of na
notube 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 an
y reasonable temperature. This result is consistent with the formation of n
anotube ropes during the high-temperature growth processes in laser vaporiz
ation and carbon are experiments.