X-ray spectra of skutterudite and filled skutterudite

X-ray near edge spectra of La-filled and unfilled skutterudites are studied by the first-principle density functional calculation. For this purpose electronic structures of LaCo₄Sb₁₂ and CoSb₃ are calculated by means of the full-potential linearized augmented plane wave (FLAPW) method with the generalized gradient approximation (GGA). As the electronic structure of skutterudite is sensitive to the lattice parameter, the lattice parameters of CoSb₃ are determined by the minimizing condition of the total energy including the spin-orbit (SO) interaction. The obtained lattice parameters are in good agreement with the experimental values. By using the determined values electronic structures of CoSb₃ and LaCo₄Sb₁₂ are calculated. The band gap of CoSb₃ is 110 meV, which is about a half of the result without SO interaction. X-ray absorption and emission near edge spectra for Co-L_III and Sb K are calculated and discussed