Ab initio study of the linear and nonlinear optical properties of chalcopyrite CdGeAs2

► We find that the charge density around the cation Cd of CdGeAs2 is spherical. ► We do not have to rely on experimental gap to determine the self-energy. ► It is the first time we have calculated the SHG susceptibility using pseudopotential plane-wave. ► The SHG susceptibility beyond zero frequency was calculated.