Density functional theory of resonant inelastic x-ray scattering in the quasi-one-dimensional dimer iridate Ba 3 InIr 2 O 9

We have investigated the electronic structure of Ba 3 InIr 2 O 9 within the density-functional theory using the generalized gradient approximation while considering strong Coulomb correlations ( GGA + U ) in the framework of the fully relativistic spin-polarized Dirac linear muffin-tin orbital band-structure method. We have studied resonant inelastic x-ray scattering (RIXS) spectra of Ba 3 InIr 2 O 9 at the Ir L 3 edge for the monoclinic C 2 / c and hexagonal P 6 3 / m m c crystal structures. The calculated results are in good agreement with experimental data. The RIXS spectrum at the Ir L 3 edge possesses several sharp features below 2 eV, corresponding to transitions within the Ir t 2 g levels. The excitation located from 2 to 5 eV is due to t 2 g → e g transitions. The wide structure situated at 5 − 12 eV appears due to charge transfer transitions. The influence of the momentum transfer vector and incident photon energy on the Ir L 3 RIXS spectrum has been investigated. Also, we have calculated the RIXS spectra of Ba 3 InIr 2 O 9 at the Ir K , M 3 , M 5 , N 3 , N 5 , and N 7 edges to study the influence of core states on the resulting Ir RIXS spectra. The theoretical RIXS spectrum at the oxygen K edge has also been analyzed.