Theoretical Study of Thorium and Uranium Tetracarbide Molecules

Abstract

Keywords: Actinides / Thorium / Uranium / Density functional calculations / Bond theoryThe electronic structure and ground-state molecular properties of neutral Th and U tetracarbides were investigated by relativistic multireference calculations using complete active space self-consistent field/multiconfiguration second-order perturbation theory (CASSCF/CASPT2) with an all-electron basis set as well as by density functional theory (B3LYP) in conjunction with relativistic pseudopotentials. The former calculations were extended with complete active space state interaction (CASSI) calculations accounting for spin-orbit coupling. The four carbon atoms can be arranged in various forms around the actinide atom to result in ten structural isomers found altogether in our study. The electronic ground state in both molecules corresponds to a planar fan-type

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

“…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).…”

Theoretical study of Pu and Am tetracarbide molecules

“…1) which has been found as the ground state of both ThC 4 and UC 4 . [21] In I the actinide atom is bonded to a bent C 4 moiety and, as the bond distances in Table 2 indicate, is bonded to all the four carbon atoms (bonding to the middle carbons is further confirmed by the bonding MO, vide infra). The C 4 moiety contains multiple delocalized carbon-carbon bonds.…”

“…[16,17] As extension toward larger carbide species, we recently completed the analysis of Th and U tetracarbides. [21] Due to several possible arrangements of the five atoms, we found 10 stable structures on the potential energy surface of those molecules. In this article, we continue this research with AmC 4 and PuC 4 molecules predicting their electronic, structural, and bonding properties by means of relativistic multireference and DFT calculations.…”

“…In our recent studies on four AnC 2 carbides (An = Th, U, Pu, Am), we have performed a detailed analysis of the possible structures and ground‐state physicochemical properties using relativistic multireference calculations . As extension toward larger carbide species, we recently completed the analysis of Th and U tetracarbides . Due to several possible arrangements of the five atoms, we found 10 stable structures on the potential energy surface of those molecules.…”

Theoretical study of the electronic spectra of neutral and cationic NpO and NpO2

“…The above described multireference methods and the ANO-RCC basis set were successfully applied in a number of studies on actinide-containing systems. 12,13,[51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67][68][69][70] The electronic spectra have been evaluated from the Einstein coefficient values (being directly related to the spectral intensities) computed at the SO-CASPT2 level. 71 The spectra were evaluated utilizing the relative populations of all computed SO states obtained by the Boltzmann equation.…”