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 LaCo/sub 4/Sb/sub 12/ and CoSb/sub 3/ 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 CoSb/sub 3/ 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 CoSb/sub 3/ and LaCo/sub 4/Sb/sub 12/ are calculated. The band gap of CoSb/sub 3/ 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/sub III/ and Sb K are calculated and discussed.