Antisites, carbon substitutionals, and vacancy defects in BN nanotubes have been investigated by first-principles total energy calculations, based on a density functional spin-polarized method. All defects introduce localized energy levels inside the band gap. For some open-shell systems (carbon substitutionals and vacancy defects) the levels in the gap region present an exchange splitting greater than 0.5 eV. The ${\mathrm{C}}_{\mathrm{B}}$ and ${\mathrm{N}}_{\mathrm{B}}$ defects, in N-rich growth condition, and ${\mathrm{C}}_{\mathrm{N}}$ in B-rich growth condition, are the ones that present the lower formation energies.

• Received 25 September 2002

DOI:https://doi.org/10.1103/PhysRevB.67.113407