Electronic and optical properties of SiGe alloys within first-principles schemes

We present first-principles calculated electronic and optical properties of some SiGe alloys. The ground-state, electronic excitations and optical properties have been calculated with Ge and Si atoms arranged in different ways among the sites of a diamond-type lattice. For the ground state a DFT-LDA scheme and for the electronic excitations a DFT-GW approach have been respectively used. For the optical properties the DFT-LDA-RPA scheme has been applied for alloys going in composition from Si(100$\%$) to Ge(100$\%$): obtained results have been compared with existing experimental and theoretical data. For the noticeable Si(50$\%$)Ge(50$\%$) alloy also two-particle effects have been evaluated using the Bethe-Salpeter equation.