Exploration of ab-initio calculations for 3d transition metal Kα X-ray Emission Spectra (XES)

Core-to-core spectroscopy is an intensely many-body problem, which makes it difficult to treat highly correlated materials such as transition metals, lanthanides, and actinides in which many body effects are prominent. I have expanded upon the work of Haverkort et al [1] to apply a DFT + MLFT approach to core-to-core XES, which is ideal for treating these highly correlated systems in a computationally efficient and accurate manner. In this approach we project the DFT calculated Bloch states onto a more localized Wannier basis, which is used to form the Tight Binding (TB) Hamiltonian that describes the system. This TB-Hamiltonian is then projected onto a symmetry reduced basis within Quanty, which is used to perform an ab-initio multiplet ligand field calculation which includes scaling of the Slater-Condon parameter, Crystal Field terms, and Charge Transfer effects. We have found excellent agreement between theory and experiment for the 3d transition metal crystalline systems that we have studied. Most notably we reproduce the spectral shift between the K-alpha XES of Cr6+ and Cr3+ materials, which has important applications to environmental safety standards.