Electronic structures of GaN nanotubes

Density functional calculations are used to predict the electronic structur es of GaN nanotubes. The graphitic GaN is an indirect band gap material wit h valence band maximum at K edge. Zigzag nanotube is a semiconductor with d irect band gap, whereas armchair nanotube has an indirect band gap along th e tube axis. The band gaps decrease with the decreasing diameter, contrary to the case of carbon nanotubes.