First-Principles Fe L2,3-Edge and O K-Edge XANES and XMCD Spectra for Iron Oxides.
Michel J SassiCarolyn I PearcePaul S BagusElke ArenholzKevin M RossoPublished in: The journal of physical chemistry. A (2017)
X-ray absorption near-edge structure (XANES) and X-ray magnetic circular dichroism (XMCD) spectroscopies are tools in widespread use for providing detailed local atomic structure, oxidation state, and magnetic structure information for materials and organometallic complexes. The analysis of these spectra for transition-metal L-edges is routinely performed on the basis of ligand-field multiplet theory because one- and two-particle mean-field ab initio methods typically cannot describe the multiplet structure. Here we show that multireference configuration interaction (MRCI) calculations can satisfactorily reproduce measured XANES spectra for a range of complex iron oxide materials including hematite and magnetite. MRCI Fe L2,3-edge XANES and XMCD spectra of Fe(II)O6, Fe(III)O6, and Fe(III)O4 in magnetite are found to be in very good qualitative agreement with experiment and multiplet calculations. Point-charge embedding and small distortions of the first-shell oxygen ligands have only small effects. Oxygen K-edge XANES/XMCD spectra for magnetite investigated by a real-space Green's function approach complete the very good qualitative agreement with experiment. Material-specific differences in local coordination and site symmetry are well reproduced, making the approach useful for assigning spectral features to specific oxidation states and coordination environments.
Keyphrases
- density functional theory
- molecular dynamics
- metal organic framework
- visible light
- transition metal
- aqueous solution
- high resolution
- systematic review
- iron oxide
- hydrogen peroxide
- molecularly imprinted
- dual energy
- molecular dynamics simulations
- optical coherence tomography
- magnetic resonance imaging
- healthcare
- computed tomography
- magnetic resonance
- electron microscopy
- nitric oxide
- monte carlo
- solid phase extraction
- liquid chromatography
- simultaneous determination