Ab initiocalculations for a hypothetical material: Silicon nanotubes

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