The role of Hartree–Fock exchange in the simulation of X-ray absorption spectra: A study of photoexcited [formula omitted

Abstract

We present a theoretical analysis for the K- and L2/3-edge static and picosecond X-ray absorption spectra of [Fe(bpy)3]2+. Simulations of the pre-edge region at the Fe K-edge using time-dependent density functional theory demonstrate the importance of Hartree–Fock exchange within the exchange–correlation functional, especially when describing charge transfer and 1s→3d transitions. This becomes particularly relevant for range separated functionals, for which the incorporation of Hartree–Fock exchange at short range decreases the absolute error in the excitation energy usually observed using TD-DFT. Finally, we compute and interpret the L2/3-edge spectrum using the Restricted Open-Shell Configuration Interaction Singles method.