To explore the theoretical aspects of Cs1-xRbxTl and K1-xRbxTl we used the different methods namely: the projector-augmented wave method (PAW) , implemented in Vienna Ab initio simulation package (VASP) and the multiple scattering Korringa-Kohn-Rostoker (KKR) Green function method as implemented in the SPRKKR code . To see an effect of disorder the coherent potential approximation (CPA) implemented in SPRKKR code was used. In both codes, our calculation are based on Perdew, Burke, and Ernzerhof generalized gradient approximation (PBE-GGA). The calculations were performed in several successive steps. The geometry optimization and electronic structure calculation was done using VASP code. All the convergence parameters in code were checked carefully.