Title :

Investigation of thermodynamics properties of gaseous plutonium oxides through a deep dive into electronic structure

Author(s) :

Kervazo, Sophie [Orateur]
Physico-Chimie Moléculaire Théorique [PCMT]
Réal, Florent [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Virot, François [Auteur]
Laboratoire d'Etude du corium et du Transfert des radioélèments [IRSN/PSN-RES/SAG/LETR]
Knecht, Stefan [Auteur]
Laboratorium für Physikalische Chemie [ETH-LPC]
Severo Pereira Gomes, Andre [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]
Vallet, Valérie [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]

Conference title :

Strasbourg satellite meeting to the 16th ICQC: Strong correlation in electronic structure theory

City :

Strasbourg

Country :

France

Start date of the conference :

2018-06-24

Publication date :

2018-06-24

HAL domain(s) :

Physique [physics]/Physique [physics]/Chimie-Physique [physics.chem-ph]

English abstract : [en]

The PUREX process has been designed for the reprocessing of spent nuclear fuel to separate uraniumand plutonium from the fission products. In accident scenario, the solvent can ignite itself, releasing involatile forms ...
Show more >The PUREX process has been designed for the reprocessing of spent nuclear fuel to separate uraniumand plutonium from the fission products. In accident scenario, the solvent can ignite itself, releasing involatile forms PuO₂, PuO₃ or PuO₂(OH)₂. Our theoretical study focusses on the thermodynamics properties of the former two species for which large experimental uncertainties remain. Actinide-containing complexes present formidable challenges for electronic structure methods due to the largenumber of degenerate or quasi-degenerate electronic states arising from partially occupied 5f and 6dshells.To compute highly accurate thermodynamics properties (enthalpies, entropies) with quantumchemical methods, static and dynamic correlation effects along with relativistic effects have to betreated on equal footing. In particular, the clear multi-reference character of the wave-function ofthese compounds requires the enthalpies of formation to be computed with multi-configurationalquantum chemical methods like CASSCF and CASPT2. Spin-orbit interaction is treated a posteriori withthe state-interaction RASSI method. The computed thermodynamics quantities reach a high accuracyallowing us to predict the composition of the released volatile products. However, in theCASSCF/CASPT2 calculations the active spaces had to be truncated, the limit of 18 electrons in 18orbitals being reached in these plutonium molecules. The Density Matrix Renormalization Group(DMRG) algorithm, which allows us to overcome the previous limit, was used in the second part of thisstudy to handle active spaces that include the full atomic valence shells. Dynamical correlation istreated with DMRG-NEVPT2, and spin-orbit interaction can then be treated with the state-interactionRASSI approach.Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Internationale

Popular science :

Non

ANR Project :

Physiques et Chimie de l'Environnement Atmosphérique

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL