title: Theoretical study of actinide monocarbides (ThC, UC, PuC, and AmC).
abstract: 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-1have 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.
authors.affiliation: European Commission, Joint Research Centre, P.O. Box 2340, 76125 Karlsruhe, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Pogány
authors.affiliation: European Commission, Joint Research Centre, P.O. Box 2340, 76125 Karlsruhe, Germany.
authors.forename: Attila
authors.initials: A
authors.lastname: Kovács
authors.affiliation: Department of Theoretical Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, NL-1081 HV Amsterdam, The Netherlands.
authors.forename: Lucas
authors.initials: L
authors.lastname: Visscher
authors.affiliation: European Commission, Joint Research Centre, P.O. Box 2340, 76125 Karlsruhe, Germany.
authors.forename: Rudy J M
authors.initials: RJ
authors.lastname: Konings