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.