Electronic structure of CeF3 and TbF3 by valence-band XPS and theory

Electronic structures of the rare earth trifluorides CeF₃ () and TbF₃ (Pnma) were examined by high-resolution valence-band X-ray photoelectron spectroscopy (VB-XPS) and all-electron periodic-crystal DFT theory including the spin-polarization (SP) combined with spin-orbit (SO) coupling using a second-variational treatment. Calculations using the Perdew-Burke-Ernzerhof (PBE) functional and the LDA+U method were carried out and compared. The results show that a complete analysis does require a full DFT-SP-SO treatment to obtain a quantitative account for the observed VB-XPS spectra, with an additional insight of the theory with regard to the nature of the topmost orbitals, and the bonding-antibonding character of orbitals within the VB and sub-VB levels. The band structure at the bottom of the conduction band (BCB) shows a strong dispersion in TbF₃ but not in CeF₃, predicting photoconductivity in TbF₃.