Three different nanotube structures, armchair, zigzag and wurtzite, were studied using B3LYP/6-31G(d) for carbon, BN, AlN and GaN nanotubes, respectively. Our calculations found that AlN and GaN can implausibly form the usual tubular morphologies of carbon and BN nanotubes. The same conclusion was confirmed based on analyzing the different configurations of benzene, borazine, and the analogies of the hexagonal Al3N3H6 and Ga3N3H6 at the same level of calculations. (c) 2005 Elsevier B.V. All rights reserved.