Theoretical Calculation of Optical Absorption Spectrum for Armchair Graphene Nanoribbon

The optical absorption spectrum of armchair graphene nanoribbon has been studied using first principle calculation. For this purpose, first we calculate the band structure and therefore the energy gap of A-GNRs by tight- binding model by including the edge deformation due to passivation of edges by hydrogen atoms. Then from single electron approximation, we obtain the real part of conductance and optical absorption of A-GNRs. Results shows that all families of A-GNRs behaves like a semiconductor and by tuning the shape and wide of ribbon one can control the energy gap and optical absorption of A-GNRs for optical applications