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

Electronic structures of the rare earth trifluorides CeF3 (P3¯c1) 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.