First-principles study of mechanical properties of one-dimensional carbon nanotube intramolecular junctions

The mechanical properties of single-walled carbon nanotubes with one-dimensional intramolecular junctions (CNT-IMJs) are investigated, using first-principles density functional theory calculations. The effects of pentagon-heptagon (5-7) defects (a pair of five- and seven-membered rings) at a junction on the Young's modulus, tensile strength, and breaking strain of CNT-IMJs are discussed from the viewpoint of charge density and interatomic distance. Our calculations indicate that the deformation concentration on a seven-membered ring causes the strength and elongation of CNT-IMJs to decrease. It is found that the tensile strength and breaking strain of CNT-IMJs depend on the position of 5-7 defects, while these properties of CNT-IMJs are not significantly affected by the number of 5-7 defects. The applicability of the AIREBO classical interatomic potential in the simulation of the tensile deformation in CNT-IMJs is also discussed.