Study of Actinides by Relativistic Coupled Cluster Methods

Eliav, Ephraim; Kaldor, Uzi

doi:10.1002/9781118688304.ch2

Cited by 9 publications

(11 citation statements)

References 98 publications

(130 reference statements)

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“…The ground state of ThO + is 2 Σ + , as identified experimentally using pulsed field ionization-zero kinetic energy photoelectron spectroscopy. 46 This state has a (1σ) 2 (1π) 4 (2σ) 1 valence electron configuration, where the 1σ and 1π orbitals are bonding orbitals formed between O (2p) and Th + (6d) orbitals and the 2σ nonbonding orbital is primarily the Th + (7s) orbital, as shown in Figure 7. Here, we calculate a bond length of 1.807 Å at the B3LYP/cc-pVQZ level, which matches the experimental bond length of 1.807, 46 as well as the bond lengths of 1.808, 1.809, and 1.808 Å calculated by Cox et al, 47 Zhou and Schlegel (ZS), 48 and Mazzone et al (MMRS), 49 respectively.…”

Section: The Journal Of Physical Chemistry Amentioning

confidence: 99%

“…3 For the radioactive elements, theoretical calculations may provide a safe and cost-effective alternative to experimental research; however, accurate quantum chemical calculations on actinide species are problematic because of the need to implement relativistic and correlation effects associated with the large number of electrons, further complicated by the close energetic proximity of many electronic states involving the 5f, 6d, 6p, and 7s orbitals. 4 The challenges of these calculations are further exacerbated by a shortage of accurate information on actinide molecules, which makes validation of the approximations employed in the theoretical models difficult. Reliable fundamental experimental benchmarks are necessary in order to investigate potential basis sets and theoretical models.…”

Section: ■ Introductionmentioning

confidence: 99%

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Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O

Kafle

Armentrout

2019

J. Phys. Chem. A

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The kinetic energy dependences of the reactions of ThO+, ThO2 +, and OThOD+ with D2O, ThO2 + with D2, and OThOD+ with Xe were studied using guided ion beam tandem mass spectrometry. Exothermic formation of OThOD+ is the dominant process observed in reactions of both ThO+ and ThO2 + with D2O. Minor products formed in endothermic reactions include ThO2 +, DThO+, and ThO2D2 +. OThOD+ is also formed in the reaction of ThO2 + with D2 but in an endothermic process. Collision-induced dissociation (CID) of OThOD+ with Xe leads to endothermic loss of the hydroxide ligand. OThOD+ reacts further with D2O to form the associative complex ThO3D3 +, which is long-lived before dissociating back to the reactants. The OThOD+–D2O bond energy of the associative complex is measured to be 2.96 ± 0.05 eV by modeling the kinetic energy-dependent cross section for association using a phase space theory model that rigorously conserves angular momentum. By comparison with theory, this bond energy identifies the ThO3D3 + species as the trihydroxide cation, Th(OD)3 +. From the endothermic reactions and CID of OThOD+ with Xe, the OTh+–D, OTh+–O, and OTh+–OD bond dissociation energies (BDEs) are measured to be 2.33 ± 0.24, 4.66 ± 0.15, and 6.00 ± 0.17 eV, respectively. All four of these BDEs are experimentally determined for the first time and agree reasonably well with values calculated at the B3LYP, B3PW91, and PBE0 levels of theory with cc-pVQZ basis sets. Complete potential energy surfaces for all reactions were calculated at the B3LYP/cc-pVTZ level and elucidate the mechanisms for all processes observed.

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Section: The Journal Of Physical Chemistry Amentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O

Kafle

Armentrout

2019

J. Phys. Chem. A

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“…During recent decades the relativistic Fock Space CC approach in both effective and intermediate Hamiltonian formulations proved its efficiency and high accuracy in challenging calculations of heavy atomic and molecular systems with dense spectra, especially in cases when both d and f atomic orbitals become valence (see also recent reviews [26,29,36]). In the non-relativistic realm the pilot implementation of the FS-CC method accounting for triple excitations and allowing the treatment of up to six valence electrons sectors was pioneered by Hughes and Kaldor in earlier 1990s; they reported calculations of electronic states of light atoms in rather modest basis sets [37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Relativistic Fock Space Coupled Cluster Method for Many-Electron Systems: Non-Perturbative Account for Connected Triple Excitations

et al. 2020

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The Fock space relativistic coupled cluster method (FS-RCC) is one of the most promising tools of electronic structure modeling for atomic and molecular systems containing heavy nuclei. Until recently, capabilities of the FS-RCC method were severely restricted by the fact that only single and double excitations in the exponential parametrization of the wave operator were considered. We report the design and the first computer implementation of FS-RCC schemes with full and simplified non-perturbative account for triple excitations in the cluster operator. Numerical stability of the new computational scheme and thus its applicability to a wide variety of molecular electronic states is ensured using the dynamic shift technique combined with the extrapolation to zero-shift limit. Pilot applications to atomic (Tl, Pb) and molecular (TlH) systems reported in the paper indicate that the breakthrough in accuracy and predictive power of the electronic structure calculations for heavy-element compounds can be achieved. Moreover, the described approach can provide a firm basis for high-precision modeling of heavy molecular systems with several open shells, including actinide compounds.

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“…In addressing actinide species, computational chemistry provides a vital route toward describing their thermochemistry, in part, due to the inherent difficulties of experimental work with such compounds . However, computational methods have their own challenges.…”

Section: Introductionmentioning

confidence: 99%

Considering Density Functional Approaches for Actinide Species: The An66 Molecule Set

Aebersold

Wilson

2021

J. Phys. Chem. A

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The importance of spin−orbit effects on the predictions of energetic properties of actinide compounds has been considered for 18 different density functionals, comparing the spin−orbit and non-spin−orbit ("standard") forms of density functional theory (DFT). A set of enthalpies of formation for 66 small actinide (Th−Am) compoundsthe An66 set, for which experimental data are availablehave been investigated. The set includes actinide halides, oxides, and oxohalides in the general form AnO m X n , where n = 0−6, m = 0−3, and X = F, Cl, Br, or I. The impact of basis set choice was investigated, and to help account for the impact of relativity, the Stuttgart general and segmented contracted atomic natural orbital (ANO) basis sets paired with small core relativistic effective core potentials (RECP) as well as all-electron calculations utilizing the third-order Douglas−Kroll−Hess were considered.

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Study of Actinides by Relativistic Coupled Cluster Methods

Cited by 9 publications

References 98 publications

Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O

Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O

Relativistic Fock Space Coupled Cluster Method for Many-Electron Systems: Non-Perturbative Account for Connected Triple Excitations

Considering Density Functional Approaches for Actinide Species: The An66 Molecule Set

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Study of Actinides by Relativistic Coupled Cluster Methods

Cited by 9 publications

References 98 publications

Mechanism and Energetics of the Hydrolysis of Th+To Form Th(OD)3+: Guided Ion Beam and Theoretical Studies of ThO+, ThO2+, and OThOD+Reacting with D2O

Mechanism and Energetics of the Hydrolysis of Th+To Form Th(OD)3+: Guided Ion Beam and Theoretical Studies of ThO+, ThO2+, and OThOD+Reacting with D2O

Relativistic Fock Space Coupled Cluster Method for Many-Electron Systems: Non-Perturbative Account for Connected Triple Excitations

Considering Density Functional Approaches for Actinide Species: The An66 Molecule Set

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Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O

Mechanism and Energetics of the Hydrolysis of Th⁺To Form Th(OD)₃⁺: Guided Ion Beam and Theoretical Studies of ThO⁺, ThO₂⁺, and OThOD⁺Reacting with D₂O