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Theoretical description of photoemission spectra was greatly improved recently by accounting for the correlations between the d electrons within the local spin density approximation (LSDA) plus dynamical mean field theory (DMFT). We assess how the LSDA+DMFT improves over the plain LSDA in the x-ray absorption spectroscopy, which is a probe of the unoccupied-states. By investigating the L2,3-edge XANES and XMCD of Fe, Co, and Ni, we find that the LSDA+DMFT improves the LSDA results, in particular concerning the assymmetry of the L3 white line. Differences with respect to the experiment, nevertheless, remain - particularly concerning the ratio of the intensities of the L3 and L2 peaks. The changes in the peak intensities invoked by the use of the LSDA+DMFT are consistent with the XMCD sum rules. Accounting for the core hole within the final state approximation does not generally improve the results. Similar conclusions follow also from our study of Heusler alloys (Cu2MnAl). This all indicates that to get more accurate L2,3-edge XANES and XMCD spectra, one has to treat the core hole beyond the final state approximation. This has been done and we will present first XANES and XMCD calculations done within the the linear response framework of the time-dependent DFT, including the DMFT. |
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