Electronic Structure and Optical Properties of Semiconducting Orthorhombic BaSi₂

Full potential linearized augmented plane wave (FPLAPW) method calculations are carried out for semiconducting orthorhombic BaSi₂. The optical properties and the origin of the different optical transitions are investigated. Our calculated band gap of 1.0918eV is indirect, which is in good agreement with the experimental result. The bonds between Ba and Si are considered to be electrovalent bond. The anisotropy in the imaginary part ε₂(ω) and real part
ε₁ (ω) of the optical dielectric tensor are analysed. The contributions of various transition peaks are explained from the imaginary part of the dielectric function.