1
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Zamani AY, Hratchian HP. Assessing the performance of ΔSCF and the diagonal second-order self-energy approximation for calculating vertical core excitation energies. J Chem Phys 2022; 157:084115. [DOI: 10.1063/5.0100638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Vertical core excitation energies are obtained using a combination of the ΔSCF method and the diagonal second-order (D2) self-energy approximation. These methods are applied to a set of neutral molecules and their anionic forms. An assessment of the results with the inclusion of relativistic effects is presented. For core excitations involving delocalized symmetry orbitals, the applied composite method improves upon the overestimation of ΔSCF by providing approximate values close to experimental K-shell transition energies. The importance of both correlation and relaxation contributions to the vertical core-excited state energies, the concept of local and non-local core orbitals, and the consequences of breaking symmetry are discussed.
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Affiliation(s)
| | - Hrant Patrick Hratchian
- Department of Chemistry & Biochemistry, University of California Merced, United States of America
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2
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Delcey MG, Lindblad R, Timm M, Bülow C, Zamudio-Bayer V, von Issendorff B, Lau JT, Lundberg M. Soft x-ray signatures of ionic manganese-oxo systems, including a high-spin manganese(V) complex. Phys Chem Chem Phys 2022; 24:3598-3610. [DOI: 10.1039/d1cp03667j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Manganese-oxo species catalyze key reactions, including C–H bond activation or dioxygen formation in natural photosynthesis. To better understand relevant reaction intermediates, we characterize electronic states and geometric structures of [MnOn]+...
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3
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Jenkins AJ, Hu H, Lu L, Frisch MJ, Li X. Two-Component Multireference Restricted Active Space Configuration Interaction for the Computation of L-Edge X-ray Absorption Spectra. J Chem Theory Comput 2021; 18:141-150. [PMID: 34908414 DOI: 10.1021/acs.jctc.1c00564] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
X-ray absorption spectroscopy is a powerful probe of local electronic and nuclear structures, providing insights into chemical processes. The theoretical prediction and interpretation of metal L-edge X-ray absorption spectra are complicated by both relativistic effects, including spin-orbit coupling and the multiconfigurational nature of the states involved. This work details an exact two-component multireference restricted active space (RAS) configuration interaction scheme that uses an exact two-component state-averaged complete active space self-consistent-field method, which includes the spin-orbit coupling in a variational manner, for the accurate description of the electronic structure before using a RAS configuration interaction method to describe the core excited states of the X-ray spectrum. Benchmark calculations are presented for a series of iron-containing complexes, with results showing key features of the spectrum being reproduced, including ligand-to-metal charge transfer and shake-up excitations.
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Affiliation(s)
- Andrew J Jenkins
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Hang Hu
- Molecular Engineering and Sciences Institute, University of Washington, Seattle, Washington 98195, United States
| | - Lixin Lu
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
| | - Michael J Frisch
- Gaussian Inc., 340 Quinnipiac Street, Building 40, Wallingford, Connecticut 06492, United States
| | - Xiaosong Li
- Department of Chemistry, University of Washington, Seattle, Washington 98195, United States
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4
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Bagus PS, Schacherl B, Vitova T. Computational and Spectroscopic Tools for the Detection of Bond Covalency in Pu(IV) Materials. Inorg Chem 2021; 60:16090-16102. [PMID: 34634201 PMCID: PMC8564760 DOI: 10.1021/acs.inorgchem.1c01331] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Plutonium is used as a major component of new-generation nuclear fuels and of radioisotope batteries for Mars rovers, but it is also an environmental pollutant. Plutonium clearly has high technological and environmental importance, but it has an extremely complex, not well-understood electronic structure. The level of covalency of the Pu 5f valence orbitals and their role in chemical bonding are still an enigma and thus at the frontier of research in actinide science. We performed fully relativistic quantum chemical computations of the electronic structure of the Pu4+ ion and the PuO2 compound. Using four different theoretical tools, it is shown that the 5f orbitals have very little covalent character although the 5f(7/2) a2u orbital with the highest orbital energy has the greatest extent of covalency in PuO2. It is illustrated that the Pu M4,5 edge high-energy resolution X-ray absorption near-edge structure (Pu M4,5 HR-XANES) spectra cannot be interpreted in terms of dipole selection rules applied between individual 3d and 5f orbitals, but the selection rules must be applied between the total wavefunctions for the initial and excited states. This is because the states cannot be represented by single determinants. They are shown to involve major redistributions on the 5f electrons over the different 5f orbitals. These redistributions could be viewed as shake-up-like excitations in the 5f shell from the lowest orbital energy from J = 5f(5/2) into higher orbital energy J = 5f(7/2). We show that the second peak in the Pu M4 edge and the high-energy shoulder of the Pu M5 edge HR-XANES spectra probe the 5f(7/2) a2u orbital; thus, these spectral features are expected to change upon bond variations. We describe theoretical and spectroscopy tools, which can be applied for all actinide elements in materials with cubic structure.
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Affiliation(s)
- Paul S Bagus
- Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, United States
| | - Bianca Schacherl
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE), P.O. Box 3640, D-76021 Karlsruhe, Germay
| | - Tonya Vitova
- Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE), P.O. Box 3640, D-76021 Karlsruhe, Germay
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5
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Mandal AK, Jana A, Chowdhury S, Tiwari A, Choudhary RJ, Phase DM. Mixed Mott-Hubbard and charge transfer nature of 4H-SrMnO 3thin film on Si (100). JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:235501. [PMID: 33973533 DOI: 10.1088/1361-648x/abe8a3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
Room temperature electronic structure of polycrystalline 4H-SrMnO3thin film grown on Si (100) substrate has been studied using resonance photo emission spectroscopy and soft x-ray absorption spectroscopy measurements. Presence of charge transfer screen Mn 3dnLfinal state along with the 3dn-1final state at the valence band edge of 4H-SrMnO3thin film confirms that the ground state is strongly mixed between Mn 3dand O 2pstates. The estimated equivalent values of on-site Coulomb interaction energy (U) and O 2pto Mn 3d- charge transfer energy (Δ) (U≈ Δ ≈ 4.8 eV) from the combination of occupied and unoccupied spectra further confirm the intermediate Mott-Hubbard and charge transfer insulator nature of 4H-SrMnO3film. Despite having similar Mn 4+ valence state in 4H-SrMnO3and cubic SrMnO3, 4H phase is observed to reveal much higher band gap ∼1.5 eV than the cubic phase (0.3 eV), which arises due to different MnO6octahedra environment.
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Affiliation(s)
- Arup Kumar Mandal
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - Anupam Jana
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - Sourav Chowdhury
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - Achyut Tiwari
- Indian Institute of Technology (Indian School of Mines), Dhanbad-826004, Jharkhand, India
| | - R J Choudhary
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
| | - D M Phase
- UGC-DAE Consortium for Scientific Research, Indore-452001, Madhya Pradesh, India
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6
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Bagus PS, Nelin CJ, Brundle CR, Crist BV, Lahiri N, Rosso KM. Combined multiplet theory and experiment for the Fe 2p and 3p XPS of FeO and Fe 2O 3. J Chem Phys 2021; 154:094709. [PMID: 33685168 DOI: 10.1063/5.0039765] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The Al K alpha, 1486.6 eV, based x-ray photoelectron spectroscopy (XPS) of Fe 2p and Fe 3p for Fe(III) in Fe2O3 and Fe(II) in FeO is compared with theoretical predictions based on ab initio wavefunctions that accurately treat the final, core-hole, multiplets. The principal objectives of this comparison are to understand the multiplet structure and to evaluate the use of both the 2p and 3p spectra in determining oxidation states. In order to properly interpret the features of these spectra and to use the XPS to provide atomistic insights as well as atomic composition, it is necessary to understand the origin of the multiplet energies and intensities. The theoretical treatment takes into account the ligand field and spin-orbit splittings, the covalent mixing of ligand and Fe 3d orbitals, and the angular momentum coupling of the open shell electrons. These effects lead to the distribution of XPS intensity into a large number of final, ionic, states that are only partly resolved with energies spread over a wide range of binding energies. For this reason, it is necessary to record the Fe 2p and 3p XPS spectra over a wide energy range, which includes all the multiplets in the theoretical treatment as well as additional shake satellites. We also evaluate the effects of differing assumptions concerning the extrinsic background subtraction, to make sure our experimental spectrum may be fairly compared to the theory. We conclude that the Fe 3p XPS provides an additional means for distinguishing Fe(III) and Fe(II) oxidation states beyond just using the Fe 2p spectrum. In particular, with the use of the Fe 3p XPS, the depth of the material probed is about 1.5 times greater than for the Fe 2p XPS. In addition, a new type of atomic many-body effect that involves excitations into orbitals that have Fe f,ℓ = 3, symmetry has been shown to be important for the Fe 3p XPS.
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Affiliation(s)
- Paul S Bagus
- Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, USA
| | | | - C R Brundle
- C. R. Brundle and Associates, Soquel, California 95073, USA
| | | | - N Lahiri
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Kevin M Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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Maganas D, Kowalska JK, Van Stappen C, DeBeer S, Neese F. Mechanism of L 2,3-edge x-ray magnetic circular dichroism intensity from quantum chemical calculations and experiment-A case study on V (IV)/V (III) complexes. J Chem Phys 2020; 152:114107. [PMID: 32199419 DOI: 10.1063/1.5129029] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In this work, we present a combined experimental and theoretical study on the V L2,3-edge x-ray absorption (XAS) and x-ray magnetic circular dichroism (XMCD) spectra of VIVO(acac)2 and VIII(acac)3 prototype complexes. The recorded V L2,3-edge XAS and XMCD spectra are richly featured in both V L3 and L2 spectral regions. In an effort to predict and interpret the nature of the experimentally observed spectral features, a first-principles approach for the simultaneous prediction of XAS and XMCD spectra in the framework of wavefunction based ab initio methods is presented. The theory used here has previously been formulated for predicting optical absorption and MCD spectra. In the present context, it is applied to the prediction of the V L2,3-edge XAS and XMCD spectra of the VIVO(acac)2 and VIII(acac)3 complexes. In this approach, the spin-free Hamiltonian is computed on the basis of the complete active space configuration interaction (CASCI) in conjunction with second order N-electron valence state perturbation theory (NEVPT2) as well as the density functional theory (DFT)/restricted open configuration interaction with singles configuration state functions based on a ground state Kohn-Sham determinant (ROCIS/DFT). Quasi-degenerate perturbation theory is then used to treat the spin-orbit coupling (SOC) operator variationally at the many particle level. The XAS and XMCD transitions are computed between the relativistic many particle states, considering their respective Boltzmann populations. These states are obtained from the diagonalization of the SOC operator along with the spin and orbital Zeeman operators. Upon averaging over all possible magnetic field orientations, the XAS and XMCD spectra of randomly oriented samples are obtained. This approach does not rely on the validity of low-order perturbation theory and provides simultaneous access to the calculation of XMCD A, B, and C terms. The ability of the method to predict the XMCD C-term signs and provide access to the XMCD intensity mechanism is demonstrated on the basis of a generalized state coupling mechanism based on the type of the excitations dominating the relativistically corrected states. In the second step, the performance of CASCI, CASCI/NEVPT2, and ROCIS/DFT is evaluated. The very good agreement between theory and experiment has allowed us to unravel the complicated XMCD C-term mechanism on the basis of the SOC interaction between the various multiplets with spin S' = S, S ± 1. In the last step, it is shown that the commonly used spin and orbital sum rules are inadequate in interpreting the intensity mechanism of the XAS and XMCD spectra of the VIVO(acac)2 and VIII(acac)3 complexes as they breakdown when they are employed to predict their magneto-optical properties. This conclusion is expected to hold more generally.
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Affiliation(s)
- Dimitrios Maganas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Joanna K Kowalska
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Casey Van Stappen
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Serena DeBeer
- Max Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, 45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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Bagus PS, Nelin CJ, Brundle CR, Lahiri N, Ilton ES, Rosso KM. Analysis of the Fe 2p XPS for hematite α Fe2O3: Consequences of covalent bonding and orbital splittings on multiplet splittings. J Chem Phys 2020; 152:014704. [DOI: 10.1063/1.5135595] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Paul S. Bagus
- Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, USA
| | | | - C. R. Brundle
- C. R. Brundle and Associates, Soquel, California 95073, USA
| | - N. Lahiri
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Eugene S. Ilton
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Kevin M. Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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9
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Bagus PS, Sassi MJ, Rosso KM. Cluster embedding of ionic systems: Point charges and extended ions. J Chem Phys 2019; 151:044107. [DOI: 10.1063/1.5108728] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Paul S. Bagus
- Department of Chemistry, University of North Texas, Denton, Texas 76203-5017, USA
| | - Michel J. Sassi
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
| | - Kevin M. Rosso
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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10
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Maganas D, Kowalska JK, Nooijen M, DeBeer S, Neese F. Comparison of multireference ab initio wavefunction methodologies for X-ray absorption edges: A case study on [Fe(II/III)Cl4]2–/1– molecules. J Chem Phys 2019; 150:104106. [DOI: 10.1063/1.5051613] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Affiliation(s)
- Dimitrios Maganas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Joanna K. Kowalska
- Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Marcel Nooijen
- Department of Chemistry, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Serena DeBeer
- Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
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11
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Multiconfigurational Approach to X-ray Spectroscopy of Transition Metal Complexes. TRANSITION METALS IN COORDINATION ENVIRONMENTS 2019. [DOI: 10.1007/978-3-030-11714-6_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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12
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Guo M, Källman E, Pinjari RV, Couto RC, Kragh Sørensen L, Lindh R, Pierloot K, Lundberg M. Fingerprinting Electronic Structure of Heme Iron by Ab Initio Modeling of Metal L-Edge X-ray Absorption Spectra. J Chem Theory Comput 2018; 15:477-489. [DOI: 10.1021/acs.jctc.8b00658] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Meiyuan Guo
- Department of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Erik Källman
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Rahul V. Pinjari
- School of Chemical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606, Maharashtra, India
| | - Rafael C. Couto
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Lasse Kragh Sørensen
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Roland Lindh
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
| | - Kristine Pierloot
- Department of Chemistry, University of Leuven, Celestijnenlaan 200F, B-3001 Heverlee Leuven, Belgium
| | - Marcus Lundberg
- Department of Chemistry - Ångström Laboratory, Uppsala University, 751 20 Uppsala, Sweden
- Department of Biotechnology, Chemistry and Pharmacy, Università di Siena, Via A. Moro 2, 53100 Siena, Italy
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Bagus PS, Nelin CJ, Sassi M, Ilton ES, Rosso KM. Consequences of realistic embedding for the L2,3 edge XAS of α-Fe2O3. Phys Chem Chem Phys 2018; 20:4396-4403. [DOI: 10.1039/c7cp06926j] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cluster models of condensed systems are often used to simulate the core-level spectra obtained with X-ray Photoelectron Spectroscopy, XPS, or with X-ray Absorption Spectroscopy, XAS, especially for near edge features.
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Affiliation(s)
- Paul S. Bagus
- Department of Chemistry
- University of North Texas
- Denton
- USA
| | | | - Michel Sassi
- Pacific Northwest National Laboratory
- Richland
- USA
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