title: Multi-reference approach to the calculation of photoelectron spectra including spin-orbit coupling.
abstract: X-ray photoelectron spectra provide a wealth of information on the electronic structure. The extraction of molecular details requires adequate theoretical methods, which in case of transition metal complexes has to account for effects due to the multi-configurational and spin-mixed nature of the many-electron wave function. Here, the restricted active space self-consistent field method including spin-orbit coupling is used to cope with this challenge and to calculate valence- and core-level photoelectron spectra. The intensities are estimated within the frameworks of the Dyson orbital formalism and the sudden approximation. Thereby, we utilize an efficient computational algorithm that is based on a biorthonormal basis transformation. The approach is applied to the valence photoionization of the gas phase water molecule and to the core ionization spectrum of the [Fe(H2O)6](2+) complex. The results show good agreement with the experimental data obtained in this work, whereas the sudden approximation demonstrates distinct deviations from experiments.
authors: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors: Gilbert
authors: G
authors: Grell
authors: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors: Sergey I
authors: SI
authors: Bokarev
authors: Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
authors: Bernd
authors: B
authors: Winter
authors: Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
authors: Robert
authors: R
authors: Seidel
authors: Helmholtz-Zentrum Berlin für Materialien und Energie, Methods for Material Development, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany.
authors: Emad F
authors: EF
authors: Aziz
authors: Chemistry Department, Faculty of Science, King Abdulaziz University, 21589 Jeddah, Saudi Arabia.
authors: Saadullah G
authors: SG
authors: Aziz
authors: Institut für Physik, Universität Rostock, D-18051 Rostock, Germany.
authors: Oliver
authors: O
authors: Kühn