title: Thermodynamic properties of gaseous ruthenium species.
abstract: The review of thermodynamic data of ruthenium oxides reveals large uncertainties in some of the standard enthalpies of formation, motivating the use of high-level relativistic correlated quantum chemical methods to reduce the level of discrepancies. The reaction energies leading to the formation of ruthenium oxides RuO, RuO2, RuO3, and RuO4 have been calculated for a series of reactions. The combination of different quantum chemical methods has been investigated [DFT, CASSCF, MRCI, CASPT2, CCSD(T)] in order to predict the geometrical parameters, the energetics including electronic correlation and spin-orbit coupling. The most suitable method for ruthenium compounds is the use of TPSSh-5%HF for geometry optimization, followed by CCSD(T) with complete basis set (CBS) extrapolations for the calculation of the total electronic energies. SO-CASSCF seems to be accurate enough to estimate spin-orbit coupling contributions to the ground-state electronic energies. This methodology yields very accurate standard enthalpies of formations of all species, which are either in excellent agreement with the most reliable experimental data or provide an improved estimate for the others. These new data will be implemented in the thermodynamical databases that are used by the ASTEC code (accident source term evaluation code) to build models of ruthenium chemistry behavior in severe nuclear accident conditions. The paper also discusses the nature of the chemical bonds both from molecular orbital and topological view points.
authors.affiliation: †Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, Cadarache, St Paul Lez Durance 13115, France.|‡PhysicoChimie des Processus de Combustion et de l'Atmosphère (PC2A), UMR 8522 CNRS/Lille1, Université Lille 1 Sciences et Technologies, Cité Scientifique, Bât C11/C5, F-59655 Villeneuve d'Ascq, Cedex, France.|§Physique des Lasers Atomes et Molécules (PhLAM), UMR 8523 CNRS/Lille1, Université de Lille, F-59655 Villeneuve d'Ascq, Cedex 59655, France.|∥Laboratoire de Recherche Commun IRSN-CNRS-Lille1 "Cinétique Chimique, Combustion, Réactivité" (C3R), Cadarache, Saint Paul Lez Durance 13115, France.
authors.forename: Faoulat
authors.initials: F
authors.lastname: Miradji
authors.affiliation: †Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, Cadarache, St Paul Lez Durance 13115, France.|∥Laboratoire de Recherche Commun IRSN-CNRS-Lille1 "Cinétique Chimique, Combustion, Réactivité" (C3R), Cadarache, Saint Paul Lez Durance 13115, France.
authors.forename: Sidi
authors.initials: S
authors.lastname: Souvi
authors.affiliation: †Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES, Cadarache, St Paul Lez Durance 13115, France.|∥Laboratoire de Recherche Commun IRSN-CNRS-Lille1 "Cinétique Chimique, Combustion, Réactivité" (C3R), Cadarache, Saint Paul Lez Durance 13115, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Cantrel
authors.affiliation: ‡PhysicoChimie des Processus de Combustion et de l'Atmosphère (PC2A), UMR 8522 CNRS/Lille1, Université Lille 1 Sciences et Technologies, Cité Scientifique, Bât C11/C5, F-59655 Villeneuve d'Ascq, Cedex, France.|∥Laboratoire de Recherche Commun IRSN-CNRS-Lille1 "Cinétique Chimique, Combustion, Réactivité" (C3R), Cadarache, Saint Paul Lez Durance 13115, France.
authors.forename: Florent
authors.initials: F
authors.lastname: Louis
authors.affiliation: §Physique des Lasers Atomes et Molécules (PhLAM), UMR 8523 CNRS/Lille1, Université de Lille, F-59655 Villeneuve d'Ascq, Cedex 59655, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Vallet