The Density Functional Theory with full potential linearized augmented plane wave uses to study the pure graphene and doped with different amounts of Germanium (5.55, 8.33, and 12.5%). It uses also Generalized Gradient Approximation and Tran-Blaha modified Becke-Johnson formalism to investigate their electronic and optical properties. Furthermore, it utilizes Germanium is able to open band gap due to the p-states of Ge, which are in hybridization with p-states of Carbon. Germanium concentration decreasing or increasing can control the band gap opening of graphene system. The optical absorption increases in the ultraviolet range, due to the important absorption that contains germanium above 150 nm.
