All-electron Douglas–Kroll–Hess and pseudopotential study on the low-lying states of uranium hydride UH

Cao, Xiaoyan; Moritz, Anna; Dolg, Michael

doi:10.1016/j.chemphys.2007.08.008

Cited by 19 publications

(27 citation statements)

References 32 publications

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“…For a DKH calculation using an allelectron basis set, Cao, Moritz, and Dolg calculated a SO correction for the ground state (mainly 4 I) of neutral UH of 0.08 and 0.12 eV depending on the method used. 112 Balasubramanian calculated an effect of 0.09 eV for UH 2 . 113 In a subsequent paper, Dolg and Cao improved their results and found a larger SO correction for UH of 0.2 eV.…”

Section: ■ Theoretical Resultsmentioning

confidence: 99%

“…The magnitude of the calculated SO correction for the UH + BDE is attributed to the difference in atomic spin–orbit corrections for U + and U 2+ . For a DKH calculation using an all-electron basis set, Cao, Moritz, and Dolg calculated a SO correction for the ground state (mainly 4 I) of neutral UH of 0.08 and 0.12 eV depending on the method used . Balasubramanian calculated an effect of 0.09 eV for UH 2 .…”

Section: Theoretical Resultsmentioning

confidence: 99%

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Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

et al. 2021

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The kinetic energy dependent reactions of the atomic actinide uranium cation (U + ) with H 2 , D 2 , and HD were examined by guided ion beam tandem mass spectrometry. An average 0 K bond dissociation energy of D 0 (U + -H) = 2.48  0.06 eV is obtained by analysis of the endothermic product ion cross sections. Quantum chemistry calculations were performed for comparison with experimental thermochemistry, including high-level CASSCF-CASPT2-RASSI calculations of the spin-orbit corrections. CCSD(T) and the CASSCF levels show excellent agreement with experiment, whereas, B3LYP and PBE0 slightly overestimate and the M06 approach badly underestimates the bond energy for UH + . Theory was also used to investigate the electronic structures of the reaction intermediates and potential energy surfaces. The experimental product branching ratio for reaction of U + with HD indicates that these reactions occur primarily via a direct reaction mechanism, despite the presence of a deep-well for UH 2 + formation according to theory. The reactivity and hydride bond energy for U + are compared with those for transition metal, lanthanide, and actinide cations, and periodic trends are discussed.These comparisons suggest that the 5f electrons on uranium are largely core and uninvolved in the reactive chemistry.

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Section: ■ Theoretical Resultsmentioning

confidence: 99%

Section: Theoretical Resultsmentioning

confidence: 99%

Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

et al. 2021

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“…It was expected that excitations from these orbitals would be unimportant for the ground and low-lying states of UF and UF + , at least near the equilibrium bond length. The same or similar active spaces were used in previous high-level studies 17,18,22,32 of UF, UH, and UH 2 . The states included in the state-averaged CASSCF calculations for UF + were quintets and triplets with Λ = 0−6, correlating with the f 3 s configuration of U 2+ , and Λ = 0−8 quintets correlating with the f 3 d configuration.…”

Section: ■ Calculationsmentioning

confidence: 99%

Spectroscopic and Theoretical Investigations of UF and UF⁺

Antonov

2013

J. Phys. Chem. A

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Laser induced fluorescence and resonantly enhanced multiphoton ionization spectra were recorded for UF in the 18,000-20,000 cm(-1) range. Rotationally resolved data were obtained, and the analysis of a band at 18624 cm(-1) yielded a ground state rotational constant of 0.2348 cm(-1). The electronic ground state was clearly identified as |Ω| = 4.5, confirming the theoretically predicted U(+)(5f(3)7s(2))F(-) configuration. Dispersed fluorescence spectra revealed low-lying electronic states that are assigned as |Ω| = 3.5 (435 cm(-1)) and 2.5 (650 cm(-1)). Two-color photoionization spectroscopy was used to study UF(+). The ground state and fifteen electronically excited states have been characterized. The ground state was found to be |Ω| = 4, as it is for the isoelectronic molecule UO, and with vibrational constants of ωe = 649.92 and ωexe = 1.83 cm(-1). The patterns of electronically excited states observed for UF(+), with |Ω| values ranging from 0 to 6, were qualitatively consistent with the predictions of a ligand field theory model developed for UO. The experimental data for both UF and UF(+) were reasonably well reproduced by CASSCF/CASPT2 electronic structure calculations that included spin-orbit coupling.

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“…To incorporate relativistic effects, various approximations to the full Dirac Hamiltonian have been used in combination with all-electron (AE) basis sets . The literature contains many examples in which the Douglas−Kroll−Hess (DKH) approximation, – the zeroth-order regular approximation – (ZORA), and other such approximations have been used to include relativistic effects in calculations on actinides. – The use of specially designed effective core potentials in place of AE basis sets is another means of including relativistic effects . These relativistic effective core potentials (RECPs) and their associated valence basis sets have been used in calculations at the density functional theory (DFT), , second-order Møller−Plesset perturbation theory – (MP2), and coupled cluster (CCSD(T)) – levels of theory.…”

Section: Introductionmentioning

confidence: 99%

Performance of Relativistic Effective Core Potentials in DFT Calculations on Actinide Compounds

Odoh

Schreckenbach

2009

J. Phys. Chem. A

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Density functional theory (DFT) calculations using relativistic effective core potentials (RECPs) have emerged as a robust and fast method of calculating the structural parameters and energy changes of the thermochemical reactions of actinide complexes. A comparative investigation of the performance of the Stuttgart small-core and large-core RECPs in DFT calculations has been carried out. The vibrational frequencies and reaction enthalpy changes of several uranium(VI) compounds computed using these RECPs were compared to those obtained using DFT and a four-component one-electron scalar relativistic approximation of the full Dirac equation with large all-electron basis sets (AE). The relativistic AE method is a full solution of the Dirac equation with all spin components separated out. This method gives the "correct" answer (with respect to scalar relativity) which should be closest to experimental values when an adequate density functional is used and in the absence of significant spin-orbit effects. The small-core RECP always show better agreement with the four-component scalar- relativistic AE method than the large-core RECP. We conclude that the 5s, 5p, and 5d orbitals are of great importance in determining the chemistry of actinide complexes. Instances in which large-core RECPs give better agreement with experimental data are attributed to either experimental uncertainties or error cancellations.

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All-electron Douglas–Kroll–Hess and pseudopotential study on the low-lying states of uranium hydride UH

Cited by 19 publications

References 32 publications

Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Spectroscopic and Theoretical Investigations of UF and UF⁺

Performance of Relativistic Effective Core Potentials in DFT Calculations on Actinide Compounds

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All-electron Douglas–Kroll–Hess and pseudopotential study on the low-lying states of uranium hydride UH

Cited by 19 publications

References 32 publications

Reactions of U+ with H2, D2, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Reactions of U+ with H2, D2, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Spectroscopic and Theoretical Investigations of UF and UF+

Performance of Relativistic Effective Core Potentials in DFT Calculations on Actinide Compounds

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Product

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Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Reactions of U⁺ with H₂, D₂, and HD Studied by Guided Ion Beam Tandem Mass Spectrometry and Theory

Spectroscopic and Theoretical Investigations of UF and UF⁺