First-principles simulation was used to investigate the structural and mechanical properties of vacancy defective single-walled (5,5) C nanotubes. The relations of the defect concentration, distribution and characteristic of defects to Young's modulus of nanotubes were quantitatively studied. It was found that each dangling-bond structure (per super-cell) decreased the Young's modulus of the nanotube by 6.1% for symmetrical distribution cases. However the concentrated vacancy structure with saturated atoms has less influence upon C nanotubes. It was suggested that the mechanical properties of C nanotubes depend strongly upon the structure and relative position of vacancies in a certain defect concentration.

Mechanical Properties of Single-Walled (5,5) Carbon Nanotubes with Vacancy Defects. S.J.Yuan, Y.Kong, F.S.Li: Chinese Physics Letters, 2007, 24[7], 2036-9