An Ab Initio Correction Vector Restricted Active Space Approach to the L‑Edge XAS and 2p3d RIXS Spectra of Transition Metal Complexes

We describe an ab
initio approach to simulate L-edge X-ray absorption
(XAS) and 2p3d resonant inelastic X-ray scattering (RIXS) spectroscopies.
We model the strongly correlated electronic structure within a restricted
active space and employ a correction vector formulation instead of
sum-over-state expressions for the spectra, thus eliminating the need
to calculate a large number of intermediate and final electronic states.
We present benchmark simulations of the XAS and RIXS spectra of the
iron complexes [FeCl4]1–/2– and
[Fe(SCH3)4]1–/2– and
interpret the spectra by deconvolving the correction vectors. Our
approach represents a step toward simulating the X-ray spectroscopies
of larger metal cluster systems that play a pivotal role in biology.