Soft X-ray spectroscopy and correlated many-electron dynamics of molecular systems from first principles theory

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X-ray spectroscopic techniques attract considerable attention, because they allow for an atom-specific probe of the local electronic structure of molecules and molecular complexes. Combined with theoretical modeling, it can be a very informative tool unraveling the state of the absorbing atom and its interactions with the environment, especially when dynamics initiated by a laser pulse is resolved in time. This project aims developing and implementing a general purpose theoretical approach to different types of soft X-ray spectroscopies, based on multi-reference techniques including spin-orbit coupling. The particular focus is put on the calculations of Auger and other autoionization processes. With this, it fills in the gap in the unified description of first-order and second-order photon-in/photon-out and photon-in/electron-out events. Such a development will make the joint analysis of different types of steady-state soft X-ray spectra more convenient and informative by providing complementary information on competing decay channels. Further, having all the couplings between states and respective decay rates at hand, a density matrix-based formalism will be implemented to study ultrafast electron and spin dynamics and to find ways to steer it by changing ultrashort pulse characteristics.