First-Principle Investigation of the Mechanical and Transport Properties of the Zigzag Carbon Nanotubes ( n , 0) ( n = 4, 5) with Stone–Wales Defects

The mechanical, electrical transport and electronic properties of perfect and with Stone–Wales defect small zigzag carbon nanotubes ( n , 0) ( n = 4, 5) were calculated using the combination of density functional theory and non-equilibrium Green function as well as tight binding methods. It is found that Stone–Wales defects can open the band gap of (5, 0) CNTs but not (4, 0) ones. Moreover, the breaking of rotational symmetry of CNTs by Stone–Wales results in falling new charge states for those delocalized electrons between the Fermi levels of the two electrodes for CNTs (5, 0). The Young’s modulus of the perfect and the Stone–Wales defected for different length, varying from 24.31 to 96.77 Å, was also investigated by the molecular dynamics method. It was found that despite perfect CNTs, with Stone–Wales defect tubes see a slight decrease in Young’s modulus by increasing the length. All in all, the effect of Stone–Wales defects on Young’s modulus of understudy nanotubes outweighs the size effects for Young’s modulus through small carbon nanotubes.