AB INITIO CALCULATIONS OF ELECTRONIC STRUCTURE AND OPTICAL SPECTRA OF (13-0) CARBON NANOTUBE

We present a first principle calculation on the electronic structure and the linear optical properties of (13-0) zigzag single walled carbon nanotube by using full potential linear augmented plane wave (FP-LAPW) method. It is found that zigzag (13-0) nanotube has semiconducting behavior with the band gap of 0.6 eV at G point. The optical spectra of (13-0) carbon nanotube have been calculated for both electric field polarizations, parallel and perpendicular to the tube axis. The dielectric function is found to be highly anisotropic and is much larger for the electric field applied along the tube axis than the perpendicular. The results show that unlike the optical absorption, the energy loss function of (13,0) SWCNT show weak anisotropy. It was also revealed that the energy loss function peaks for both electric fields happen almost at the same energies, but with rather difference in their amplitudes.