ABSTRACT
The generalized tight-binding model, with the exact diagonalization method, is developed to investigate optical properties of graphene in ve kinds of external elds. The quite large Hamiltonian matrix is transferred into the band-like one by the rearrangement of many basis functions; furthermore, the spatial distributions of wave functions on distinct sublattices are utilized to largely reduce the numerical computation time. The external elds have a strong inuence on the number, intensity, frequency, structure, and the selection rule of absorption peaks. The optical spectra in a uniform magnetic eld exhibit plentiful symmetric absorption peaks and obey a specic selection rule. However, there are many asymmetric peaks and extra selection rules under the modulated electric eld, the modulated magnetic eld, the composite electric and magnetic elds, and the composite magnetic elds.
