Modulation of curved graphene nanoribbon optical absorption spectra by an electric field

The optical absorption spectra of curved graphene nanoribbons exhibit rich dependence on the magnitude and direction of the electric field. The wave functions have spatial symmetry originating from the equivalence of the two sublattices. There exists an optical selection rule caused by the special structure of the Hamiltonian matrix and the wave function spatial symmetry. An electric field may or may not disrupt such spatial symmetry depending on its direction and magnitude. Therefore, the optical selection rule can be controlled. In addition, the two-fold degeneracy of the optical absorption peaks is lifted by the electric field, and the variations of the absorption peak energies with the field are explored.