First principles calculations for electronic band structure of single-walled carbon nanotube under uniaxial strain

Electronic band structures of single-walled carbon nanotubes (SWNTs) are studied using first principles ultrasoft pseudopotential with plane wave basis. We find that band gap values of relaxed SWNTs in the generalized gradient approximation significantly differ from those obtained in the local density approximation for the exchange-correlation functional. In addition, it is shown that electronic band structures and total energies of SWNTs are strongly correlated with axial strain.