Cluster model calculations of the filling-controlled YVO₃ and CaVO₃ compounds

We studied the electronic structure of the filling-controlled YVO₃ and CaVO₃ compounds using a cluster model. The calculations included additional non-local screening channels (a coherent screening in metallic CaVO₃ and a Mott-Hubbard screening in insulating YVO₃). The cluster model results are in good agreement with previous photoemission and X-ray absorption spectra. In CaVO₃, the coherent structure is mostly due to a coherent screened 3d¹C̱ state, whereas the incoherent feature is mainly related to a ligand screened 3d¹Ḻ state. In YVO₃, the incoherent feature remains mainly related to a ligand screened 3d²Ḻ state, but the Mott-Hubbard screened 3d²Ḏ state appears at higher energies. The opening of the band gap is related to the transfer of spectra weight, from the 3d¹C̱ state in metallic CaVO₃ to the 3d²Ḏ in insulating YVO₃. The band gap in insulating YVO₃ scales mainly with the charge-transfer energy Δ. Further, the larger orthorhombic distortion in YVO₃ also favors the insulating state. The results show that CaVO₃ is closer to the charge-transfer than to the Mott-Hubbard regime. On the other hand, the YVO₃ compound is in a heavily O 2p-V 3d mixed intermediate regime. The lowest energy charge fluctuations explain the changes in the Hall resistance R_H.