Electronic and structural properties of a hypothetical material, silicon na
notubes, are examined through first-principles calculations based on densit
y functional theory. Even considering that Si nanotubes have never been obs
erved, this paper attempts to establish the theoretical similarities betwee
n Si and C, like band structures and density of states, as well as the main
differences, especially associated with cohesive energies. The band-struct
ure calculations for silicon nanotubes show that, similar to carbon structu
res, depending on their chiralities, they may present metallic (armchair) o
r semiconductor (zigzag and mixed) behaviors.