Electronic band-edge structure, effective masses, and optical absorption of Si1-xGe x using an extended FPLAPW/VCA/LDA+U computational method

Electronic band-edge structure and optical properties of Si1-xGe x are investigated theoretically emloying a full-potential linearized augmented plane wave (FPLAPW) method. The exchange-correlation potential in the local density approximation (LDA) is corrected by an on-site Coulomb potential (i.e., within the LDA+U SIC approach) acting asymmetrically on the atomic-like orbitals in the muffin-tin spheres. The electronic structure of the Si1-xGe x is calculated self-consistently, assuming a Td symmetrized Hamiltonian and a linear behavior of the valence-band eigenfunctions for Si, SiGe, and Ge ...