A theoretical investigation of electronic and optical properties of (6,1) single-wall carbon nanotube (SWCNT)

We report the comparative study of electronic and optical properties of (6,1) SWCNT from GGA and DFT-1/2 methods. (6,1) SWCNT is a low-bandgap semiconductor, which falls within (n(1) - n(2))/3 not equal integer. The calculated bandgaps are 0.371 eV and 0.462 eV from GGA and DFT-1/2, respectively. Thus, DFT-1/2 enhanced the electronic bandgap by 24.52%. From both GGA and DFT-1/2 approaches (6,1) SWCNT exhibits an indirect bandgap along Gamma - Delta symmetry. However, the percentage change in direct-indirect bandgap is negligibly small, i.e., 4.1% and 3.7% from GGA and DFT-1/2, respectively. The refractive index measured along x-axis (n(x)) approaches unity, indicating transparent behaviour, while that along z-axis (n(z)) goes as high as similar to 3.82 for photon energy 0.0 - 0.15 eV, exhibiting opaque behaviour. Again, the value of n(z) drops below unity at photon energy similar to 0.18 eV and again approaches similar to 1 for higher energy ranges. The optical absorption is highly anisotropic and active within the infrared region.

Automated summary

The (6,1) SWCNT is a low-bandgap semiconductor with slightly different electronic bandgap values calculated from GGA and DFT-1/2 methods. Its optical properties are highly anisotropic and active in the infrared region.