Molecular-cluster study of core-level x-ray photoelectron spectra: Application to FeCl2

Core-electron-removal energies representing both main-line and satellite features in core-level x-ray photoelectron spectra are calculated for FeCl2 with use of a self-consistent embedded-cluster model. Energies are obtained by using the Slater transition-state scheme in both relativistic and nonrelativistic versions of a moment-polarized discrete variational method code. In the model calculations, spectral peaks correspond to energy differences between the ground state and ''well-screened'' or ''poorly-screened'' final states. The study includes considerations of exchange, basis set, effects associated with finite cluster size (e.g., cluster charge), and the correspondence between relaxation and excitation processes. Observed main-line and satellite spectra are successfully calculated, provided that the core hole is treated self-consistently, both with respect to the Hamiltonian and with respect to the choice of variational basis