Strain Induced Insulator-Metal Transition in Single Wall Carbon Nanotubes

In terms of a single-π orbital model, an analytical expression of the lowest-lying conduction-band and the highest-lying valence-band is derived for single wall carbon nanotubes under both the uniaxial and torsional strains. We observe not only semiconductor-metal transitions in primary metallic tubes, but also insulator-metal transitions in semiconducting tubes. Additionally, an indirect transition of electrons and a quantized electron-resonance have been expected in optical spectrum experiments of the nanotubes.