Optical Properties of Chiral Graphene Nanoribbons: a First Principal   Study
  In this paper, optical properties of Chiral Graphene Nanoribbons both in longitude and transverse polarization have been studied using density functional theory calculation. It has been shown that the selection rule which have been reported before for Armchair and Zigzag Graphene Nanoribbons are no longer valid due to breaking symmetry on these new categorize of graphene nanoribbons. However, still the edge states play a critical role in optical absorption. It have been illustrated that depending on the polarization of incident beam the absorption peaks are different while it is spread in the same energy range. It is also suggested that the absorption of light is sensitive to the chiral vector on the edges and direction of the light polarization. Due to breaking symmetry in chiral graphene nanoribbons, absorption peak is changed and it would be around 1000nm, introducing a new potential of graphene nanoribbons for optoelectronic devices. 
M. Berahman, M. Asad and M. H. Sheikhi
cond-mat.mes-hall