Theoretical investigation of NpC, NpC2 and NpC4 molecules

Pogány, Péter; Kovács, Attila

doi:10.1007/s11224-015-0641-5

Cited by 7 publications

(8 citation statements)

References 40 publications

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“…21 The calculated NBO charges of actinides in the ground-state structures were 0.99, 0.86, 0.80, 0.92, and 0.80e for ThC, UC, NpC, PuC, and AmC, respectively. The latter quite small atomic charges of the actinide atoms point to the importance of MO interactions in actinide monocarbides.…”

Section: Bonding Properties and Dissociationmentioning

confidence: 93%

“…Yet, only four theoretical studies dealt with AnC molecules (UC, 19,20 NpC, 21 and PuC 22 ) until now, providing very limited information on their molecular properties. In contrast, the di-, 21,[23][24][25][26] tri-, 27,28 and tetracarbides 18,20,21,29 of Th, U, Np, Pu, and Am have been quite extensively explored by advanced quantum chemical calculations. The lack of reliable information on the monocarbides is the motivation to our present study in which we apply relativistic multireference and density functional theory (DFT) methods to elucidate the electronic structure and other molecular characteristics of the most important monocarbides (ThC, UC, PuC, and AmC).…”

Section: Introductionmentioning

confidence: 99%

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Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Pogány

Kovács

Visscher

et al. 2016

The Journal of Chemical Physics

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A study of four representative actinide monocarbides, ThC, UC, PuC, and AmC, has been performed with relativistic quantum chemical calculations. The two applied methods were multireference complete active space second-order perturbation theory (CASPT2) including the Douglas-Kroll-Hess Hamiltonian with all-electron basis sets and density functional theory with the B3LYP exchange-correlation functional in conjunction with relativistic pseudopotentials. Beside the ground electronic states, the excited states up to 17 000 cm−1 have been determined. The molecular properties explored included the ground-state geometries, bonding properties, and the electronic absorption spectra. According to the occupation of the bonding orbitals, the calculated electronic states were classified into three groups, each leading to a characteristic bond distance range for the equilibrium geometry. The ground states of ThC, UC, and PuC have two doubly occupied π orbitals resulting in short bond distances between 1.8 and 2.0 Å, whereas the ground state of AmC has significant occupation of the antibonding orbitals, causing a bond distance of 2.15 Å.

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Section: Bonding Properties and Dissociationmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Pogány

Kovács

Visscher

et al. 2016

The Journal of Chemical Physics

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“…The global minimum is predicted to be a C 2v -symmetric (T-shape) U(C 2 ) isomer, with an energy lying more than 240 kJ/mol lower than that of the linear species. ,, Recent theoretical studies on uranium dicarbide include the adsorption of the linear and T-shape uranium dicarbide isomers on a graphene surface . Other studies on actinide carbides include a very recent work on NpC, NpC 2 , and NpC 4 …”

Section: Introductionmentioning

confidence: 99%

Molecular Structure and Bonding in Plutonium Carbides: A Theoretical Study of PuC₃

et al. 2016

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The most relevant species of plutonium tricarbide were characterized using theoretical methods. The global minimum is predicted to be a fan structure where the plutonium atom is bonded to a quasi-linear C 3 unit. A rhombic isomer, shown to be a bicyclic species with transannular C−C bonding, lies about 39 kJ/mol above the fan isomer. A linear PuCCC isomer and a three-membered ring CPuC 2 isomer were found to be higher in energy (150 and 195 kJ/ mol, respectively, above the predicted global minimum). The possible processes for the formation of these species are discussed, and the IR spectra were predicted to help in possible experimental detection. The nature of the Pu−C interaction has been analyzed in terms of a topological analysis of the electronic density, showing that Pu−C bonding is essentially ionic with a certain degree of covalent character. 51 out recently. 9−11 An important conclusion from these studies is 52 that the most stable species is not always observed in the 53 experiments. For example, the linear uranium dicarbide 54 observed in the experiments, 6,7 CUC, is not the lowest-lying 55 isomer of uranium dicarbide. The global minimum is predicted 56 to be a C 2v-symmetric (T-shape) U(C 2) isomer, with an energy 57 lying more than 240 kJ/mol lower than that of the linear 58 species. 7,9,10 Recent theoretical studies on uranium dicarbide 59 include the adsorption of the linear and T-shape uranium 60 dicarbide isomers on a graphene surface. 12 Other studies on 61 actinide carbides include a very recent work on NpC, NpC 2 , 62 and NpC 4. 13 63 On the other hand, little is known about the molecular 64 structure of small plutonium carbides. Datta et al. 5 observed 65 PuC n + ions through radio-frequency spark source mass 66 spectrometry studies, but no structural information is available 67 from these experiments. In a recent study by Pogany et al., 14 68 triangular PuC 2 was predicted from theoretical calculations to 69 lie about 381 kJ/mol below CPuC in energy. The molecular 70 structure of PuC 4 has also been theoretically studied in another 71 paper by Pogany et al., 15 which predicted a fan-type structure as 72 the most stable isomer. To the best of our knowledge, no 73 information is available for other plutonium carbides. In the 74 present work, a theoretical study of the next member in this 75 series is provided. The aim of the present work was to

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“…20 The ground states for actinide monocarbides have been predicted by relativistic multireference calculations as 3 Σ + , 4 H, 5 H, 7 F, and 3 Σ + for AnC (An: Th, U, Np, Pu, and Am), respectively. 21,22 The UC 2 was identified as being a linear CUC molecule and the bent ThC 2 are energetically favored. 23 The UC 3 and PuC 3 clusters from global-minimum searching results adopt fan-like structures via the bonding of actinides to the C 3 unit.…”

Section: Introductionmentioning

confidence: 99%

“…Actinide carbides have attracted increasing interest recently due to their potential application in nuclear fast reactors and propulsion reactors. − Especially, uranium carbide exists in a variety of stoichiometric ratios as hard and refractory ceramic materials, including UC, U 2 C 3 , and UC 2 , which are stable in molecules and contain multiple bonds . The ground states for actinide monocarbides have been predicted by relativistic multireference calculations as 3 Σ + , 4 H, 5 H, 7 F, and 3 Σ + for AnC (An: Th, U, Np, Pu, and Am), respectively. , The UC 2 was identified as being a linear CUC molecule and the bent ThC 2 are energetically favored . The UC 3 and PuC 3 clusters from global-minimum searching results adopt fan-like structures via the bonding of actinides to the C 3 unit. , From then on, the actinide tetracarbide clusters (AnC 4 , An: Th, U, Np, Pu, and Am) and actinide hexacarbides (ThC n , UC 6 and PuC 6 , n = 1–7) have been theoretically predicted to possess a planar sector structure in which actinide atoms are connected to fan-shaped C 4 and C 6 , respectively. ,− Although a series of gas-phase molecular species, like An m C n + ( m = 2, n = 2–18, An = Th, U) have been produced by laser ionization of AnC 4 alloys, only An 2 C 3 and An 2 C 4 have been structurally assigned, which contain An–C 2 bonds similar to those in U(C 2 ) 2 and U(C 2 ) 3 molecules produced by the reaction of the U atom and carbon atom .…”

Section: Introductionmentioning

confidence: 99%

12-Membered Ring Carbides with Stabilization of Actinide Atoms

et al. 2022

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Actinide (Th and U) carbides as the potential nuclear fuels in nuclear reactors require basic research in order to understand the thermodynamic stability and performance of these substances. Here we report the structural characterization and bonding analyses of [C12], ThC12, and UC12 clusters via a global-minimum search combined with relativistic quantum chemistry calculations to elucidate the stability and bonding nature of An–C bonds. We predict that these [C12], ThC12, and UC12 compounds have a planar structure with C 6h , D 12h , and D 12h symmetry, respectively. [C12] has a hyperconjugation structure containing alternating single and double bonds. The significant stabilization when forming AnC12 predominantly comes from the electrostatic interaction between An4+ and [C12]4– and also from a certain degree of orbital interaction between the An 5f6d7s valence shell and [C12] π orbitals. The covalent character of the An–C bonds exhibits a direct in-plane σ-type overlap of the C 2p-derived MOs of [C12] and the An 5fϕ AO, thus leading to an unprecedented electronic configuration of d1f1 for U in UC12. Our results present an example of the novel properties that can be expected for actinide compounds and would provide the knowledge required to obtain novel structures of AnC12 in future experiments.

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Theoretical investigation of NpC, NpC2 and NpC4 molecules

Cited by 7 publications

References 40 publications

Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Molecular Structure and Bonding in Plutonium Carbides: A Theoretical Study of PuC₃

12-Membered Ring Carbides with Stabilization of Actinide Atoms

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Theoretical investigation of NpC, NpC2 and NpC4 molecules

Cited by 7 publications

References 40 publications

Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC)

Molecular Structure and Bonding in Plutonium Carbides: A Theoretical Study of PuC3

12-Membered Ring Carbides with Stabilization of Actinide Atoms

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Molecular Structure and Bonding in Plutonium Carbides: A Theoretical Study of PuC₃