Comparative study of electronic and optical properties of graphene and germanene: DFT study

We have performed a first-principle study of the electronic and optical properties of optimized structure of germanene and graphene by means of density functional theory, using the full potential linearized augmented plane wave (FP-LAPW) method based to Gradient Generazed approximation (GGA). Moreover, the enhanced absorption coefficient, reflectivity and refraction index are also study in both directions. In general, the calculated results indicate that the graphene and germanene are similar electronic structure with zero band gap at K point, further the absorption coefficient and reflectivity of germanene is higher in visible light than graphene; germanene holds great potential solar cell applications.