Time-dependent density functional theory applied to x-ray absorption spectroscopy

We report the implementation of a time-dependent density functional theory (TDDFT) method in the adiabatic limit (TDLDA) of the calculation of x-ray absorption spectroscopy. We show results for various choices for the exchange-correlation kernel, in particular the absorption spectra at the L-2,L-3 edges of the 3d elements. We equally present a detailed study of the method's limitations and range of applicability. We found that TDDFT calculations should be performed fully relativistically even for nonmagnetic materials. We conclude that an accurate TDDFT description of x-ray absorption should include the core hole effects. The local (both in space and time) TDDFT kernels that are currently used in the description of extended systems do not meet this criterion.