First-principles calculations of the elastic, electronic, and optical properties of the filled skutterudites CeFe₄P₁₂ and ThFe₄P₁₂

The complex density-functional theory calculations of structural, electronic, and optical properties for two principal representatives of the filled skutterudites CeFe₄P₁₂ and ThFe₄P₁₂ have been reported using the full-potential linearized augmented plane-wave method plus local orbitals, as implemented in the WIEN2K code. In this approach, the local-density approximation is used for the exchange-correlation potential. We performed these calculations with and without spin-orbit interactions. Results are given for lattice constant, bulk modulus, and its pressure derivative. Band structure, density of states, pressure coefficients of energy gaps, and refractive indices are also given. We note that both CeFe₄P₁₂ and ThFe₄P₁₂ are semiconductors with indirect and direct energy gaps, respectively. The valence-band maximum is located at Γ for both compounds, whereas the conduction-band minimum is located at Γ for ThFe₄P₁₂ and at N for CeFe₄P₁₂. Our results are compared with previous theoretical calculations and experimental data.