Restricted active space simulations of the metal L-edge X-ray ab-sorption spectra and resonant inelastic x-ray scattering: revisiting [CoII/III(bpy)3]2+/3+ complexes
The electronic structure of a compound plays a key role in its functionality and hence its applications. Core-level x-ray spectroscopy technique at the the metal L-edge is widely used for probing the valence electronic structure. The x-ray spectral features at metal L-edge energy regime are usually complicated by a multitude of interactions, which make it challenging to interpret. The x-ray absorption spectrum (XAS) and the resonant inelastic x-ray scattering (RIXS) at cobalt L-edge energy regime of tris(2,2’-bipyridine) cobalt complexes [CoII(bpy)3]2+ and [CoIII(bpy)3]3+ are calculated using ab initio restricted active space (RAS) approach. The experimental spectra are nicely reproduced and their spectral features are interpreted in terms of the orbital contributions and the final-state contributions. Unbiased assignments on the spin state of the ground state of these two cobalt compounds have been critically assessed through valence-excited state calculations, the fingerprints of the x-ray spectral features together with the calculations of the branching ratio.