Stability and electronic structure of BxNyCz nanotubes

We apply a first-principles method, based on the density functional theory, to calculate the structural stability and electronic properties of BxNyCz 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 BC2N 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.