Stability and electronic structure of BxNyCznanotubes

We apply a first-principles method, based on the density functional theory, to calculate the structural stability and electronic properties of B x N y C z nanotubes. We follow the evolution of the electronic and structural properties as a function of the composition, atomic structure and nanotube diameter. The results indicate that nanotubes present a large variety of electronic properties, showing a remarkable dependence on these parameters. The formation energy decreases with the tube diameter, D , and has a strong dependence on the tube stoichiometry. Additionally, the results show that the strain energy of the tubes, relative to the corresponding unstrained sheet material, varies as 1/ D n . For BC 2 N the classical strain law ( n = 2) is clearly obtained. Nevertheless, in the case of BCN, the exact value of n is a matter of discussion.