First Principles Theorie zur Beschreibung weicher Röntgenspektroskopie und korrelierter Vielelektronendynamik in molekularen Systemen

• Antragsteller: Professor Dr. Oliver Kühn, seit 1/2021
• Fachliche Zuordnung: Theoretische Chemie: Elektronenstruktur, Dynamik, Simulation
• Förderung: Förderung von 2017 bis 2022
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 390710146

• Erstellungsjahr: 2022

Zusammenfassung der Projektergebnisse

X-ray spectroscopy, especially when equipped with time-resolution, is a powerful tool for studying matter due to its element-specificity and local probe of the electronic structure of a particular type of atoms embedded in their chemical environment. Due to the complexity of the experimentally detected signals and addressed processes, assistance from theoretical modeling is mandatory. In view of these applications, the project was devoted to the development of theory and its practical implementation. In particular, the project resulted in the establishment of the computational protocols to address the ionization and autoionization (Auger-Meitner) spectra and the ultrafast electron dynamics caused by electron relaxation and correlation as well as spin dynamics driven by strong spin-orbit coupling. Importantly, the electronic structure of the studied systems is treated at the multi-configurational level, e.g., making studies of transition metal complexes routinely available. A hierarchy of the methods for the (auto)ionization has been established allowing to find a balance between accuracy and time of calculation for the particular system and problem at hand. For instance, the one-center approximation appeared to be especially effective while calculating the Auger spectra of molecules with only minor or no loss of accuracy. Further, a method of computing ionization cross sections has been developed which avoids evaluating the bound-continuum integrals. It is based on the solving driven-type Schrödinger equation leading to a unique continuum functions which are specific to the given transition and details of light-matter interaction in contrast to the conventional approach. Finally, the dynamical protocol allows to address non-linear processes and spectra in a nonperturbative regime, as well as to study the charge dynamics, e.g., molecular charge migration, and spin dynamics in the ionized and core-excited states. All this developments are incorporated within the open-source OpenMolcas program package enabling usage by a large community of theoretical chemists. The introduced advancements are anticipated to broaden our understanding of ultrafast electronic processes in molecules at the atomic level.

Projektbezogene Publikationen (Auswahl)

• OpenMolcas: From Source Code to Insight, J. Chem. Theory Comput. 15, 5925 (2019)
  I. Fernández Galván, M. Vacher, A. Alavi, C. Angeli, F. Aquilante, J. Autschbach, J.J. Bao, S.I. Bokarev, N.A. Bogdanov, R.K. Carlson, L.F. Chibotaru, J. Creutzberg, N. Dattani, M.G. Delcey, S.S. Dong, A. Dreuw, L. Freitag, L.M. Frutos, L. Gagliardi, F. Gendron, A. Giussani, L. González, G. Grell, M. Guo, C.E. Hoyer, M. Johansson, E. Källman, S. Keller, S. Knecht, G. Kovačević, G. Li Manni, M. Lundberg, Y. Ma, S. Mai, J. P. Malhado, P.-Å. Malmqvist, Ph. Marquetand, St.A. Mewes, J. Norell, M. Olivucci, M. Oppel, Q.M. Phung, K. Pierloot, F. Plasser, M. Reiher, A.M. Sand, I. Schapiro, P. Sharma, L.K. Sørensen, Ch. Stein, D.G. Truhlar, M. Ugandi, L. Ungur, A. Valentini, St. Vancoillie, V. Veryazov, P.-O. Widmark, S. Wouters, J.P. Zobel, R. Lindh
  
• Effect of chemical structure on the ultrafast spin dynamics in core-excited states, J. Chem. Phys. 153 (2020), 044304
  V. Kochetov, H. Wang, S.I. Bokarev
  
• Multi-reference protocol for (auto)ionization spectra: Application to molecules. J. Chem. Phys. 152 (2020) 074108
  G. Grell, S.I. Bokarev
  
• Computing photoelectron spectra employing unique continuum functions, Phys. Rev. A., 106 (2022), 032806
  T. Marx, S.I. Bokarev
  
• Multireference Approach to Normal and Resonant Auger Spectra Based on the One-Center Approximation, J. Chem. Theory Comput., 18 (2022) 4387-4407
  B.N.C. Tenorio, T.A. Voß, S.I. Bokarev, P. Decleva, S. Coriani
  
• Probing the molecular structure of aqueous triiodide via X-ray photoelectron spectroscopy and correlated electron phenomena, Phys. Chem. Chem. Phys., 24 (2022) 15540-15555
  S. Md Ahsan, V. Kochetov, D. Hein, S.I. Bokarev, I. Wilkinson
  
• RhoDyn: A ρ-TD-RASCI Framework to Study Ultrafast Electron Dynamics in Molecules, J. Chem. Theory Comput., 18 (2022) 46-58
  V. Kochetov, S.I. Bokarev