First-Principles Fe L _2,3 -Edge and O K-Edge XANES and XMCD Spectra for Iron Oxides

Journal Article · Mon Oct 02 00:00:00 EDT 2017 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI:https://doi.org/10.1021/acs.jpca.7b08392· OSTI ID:1422339

Sassi, Michel  ^[1]; Pearce, Carolyn I. ^[1]; Bagus, Paul S. ^[2]; Arenholz, Elke ^[3]; Rosso, Kevin M.  ^[1]

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1. Pacific Northwest National Laboratory, Richland, Washington 99352, United States
2. Department of Chemistry, University of North Texas, Denton, Texas 76203, United States
3. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States

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.

• Research Organization: Pacific Northwest National Lab. (PNNL), Richland, WA (United States). Environmental Molecular Sciences Lab. (EMSL)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1422339
• Report Number(s): PNNL-SA-131673; 47824; KC0302060
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Vol. 121, Issue 40; ISSN 1089-5639
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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