Abstract
Structural and electronic properties as well as the stability of nanotubes are studied using the density-functional-based tight-binding method. It is found that zigzag ( ) nanotubes exhibit a narrow direct band gap and armchair ( ) possess a nonzero moderate direct gap. Interestingly, the ( ) tubes show a small indirect gap similar to the direct gap of ( ) nanotubes. Simulated electron diffraction patterns confirm the existence of armchair and zigzag disulphide nanotubes. The structure of the nanotube tips is explained by introducing topological defects which produce positive and negative curvature.
- Received 4 November 1999
DOI:https://doi.org/10.1103/PhysRevLett.85.146
©2000 American Physical Society