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DOE OSTI · 1870985

Two-Component Multireference Restricted Active Space Configuration Interaction for the Computation of L-Edge X-ray Absorption Spectra

Jenkins, Andrew J.·Hu, Hang·Lu, Lixin·Frisch, Michael J.·Li, Xiaosong
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Abstract

X-ray absorption spectroscopy is a powerful probe of local electronic and nuclear structure, providing insights into chemical processes. The theoretical prediction and interpretation of metal L-edge X-ray absorption spectra is complicated by both relativistic effects, including spin-orbit coupling, and by the multiconfigurational nature of the states involved. This work details an exact two-component multireference restricted active space configuration interaction (X2C-MRRASCI) scheme that uses an exact two-component state average complete active space self-consistent-field method (X2C-SA-CASSCF), which includes the spin-orbit coupling in a variational manner, for the accurate description of the electronic structure before using a restricted active space configuration interaction method to describe the core excited states of the X-ray spectrum. Benchmark calculations are presented for a series of iron containing complexes, with results showing key features of the spectrum being reproduced, including ligand to metal charge transfer and shake-up excitations.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS74 ATOMIC AND MOLECULAR PHYSICS

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Jenkins, Andrew J., Hu, Hang, Lu, Lixin, Frisch, Michael J., Li, Xiaosong. 2021-12-15. Two-Component Multireference Restricted Active Space Configuration Interaction for the Computation of L-Edge X-ray Absorption Spectra. https://doi.org/10.1021/acs.jctc.1c00564

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