Metallic–semiconducting transition of single-walled carbon nanotubes under high axial strain

Carbon nanotubes (CNTs) have been attracting attention because of their characteristic mechanical and electronic properties. It has been pointed out that a single-walled CNT can stretch in the axial direction at 30% strain without any bonds breaking. Therefore, it is of interest to investigate electronic properties of CNTs under high axial strain. In this study, we investigate the change in electronic properties of single-walled CNTs under high axial strain with tight-binding semiempirical band calculations. The property of CNTs with the chiral vectors, (m,n); m−n=3q, where m, n and q are integers, shows the transition, metallic → semiconducting → metallic in that order under tension, except armchair tubes, which remain metallic. The transition in CNTs with the chiral vectors of m−n=3q+1 or m−n=3q+2 is: semiconducting → metallic → semiconducting, and the transient strain is dependent on the diameter of the CNTs.