Effect of strain on the band gap and effective mass of zigzag single-wall carbon nanotubes: First-principles density-functional calculations

We have studied the behavior of band gap and effective mass of both the electrons and the holes in small diameter zigzag single-walled carbon nanotubes under uniaxial mechanical strain by using first-principles density-functional theory. The band gap of these nanotubes is modified by both compressive and tensile strain and all zigzag single-wall carbon nanotubes show a semiconductor-metal transition with strain. We also find that both compressive and tensile strains have a similar effect on the effective mass of the electrons and holes in these nanotubes. Our studies also show that the response of the changes in band gap and effective mass to the uniaxial strain could be grouped into three categories, depending on their chirality.