Ab initio calculations of the Ni K-edge XANES in Ni_cMg _1-cO solid solutions

An interpretation of the Ni K-edge X-ray absorption near edge structure (XANES) in pure NiO and Ni_cMg_1-cO solid solutions is given based on three types of ab initio theoretical calculations: the full-multiple-scattering (FMS) approach, the finite difference method (FDM) and the full potential linear muffin-tin orbital (FP-LMTO) method within the LSDA+U approach. The first two methods differ in the cluster potential approximation: the spherically symmetric muffin-tin potential is used in the FMS approach, whereas a non-muffin-tin numerical potential makes the core of the FDM. We found that the FMS and FDM techniques allow rather accurate description of the experimental XANES signal especially above the absorption edge and produce close results, the FP-LMTO is more accurate close to the absorption edge.