First-principles study of substitutional carbon pair and Stone-Wales defect complexes in boron nitride nanotubes

► We study the substitutional carbon pair and Stone-Wales defect complexes in boron nitride nanotubes. ► Formation energy of SW defect of the carbon dimer is lower than that of a B-N pair. ► This phenomenon may be experimentally observed with a higher probability. ► We discuss the localized states originating from the carbon pair impurities.