Dissertation / PhD Thesis

FZJ-2016-03203

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Feasible and Reliable Ab initio Atomistic Modeling for Nuclear Waste Management

Beridze, G. (Corresponding author)FZJ*

2016
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich
ISBN: 978-3-95806-151-4

Please use a persistent id in citations: http://hdl.handle.net/2128/11604  urn:nbn:de:0001-2016072900

Abstract: The studies in this PhD dissertation focus on finding a computationally feasible $\textit{ab initio}$ methodology which would make the reliable first principle atomistic modeling of nuclear materials possible. Here we tested the performance of the different DFT functionals and the DFT-based methods that explicitly account for the electronic correlations, such as the DFT$\textit{+U}$ approach, for prediction of structural and thermochemical properties of lanthanide- and actinide-bearing materials. In the previous studies,the value of the Hubbard $\textit{U}$ parameter, required by the DFT$\textit{+U}$ method, was often guessed or empirically derived. We applied and extensively tested the recently developed ab initio methods such as the constrained local density approximation (cLDA)and the constrained random phase approximation (cRPA), to compute the Hubbard $\textit{U}$ parameter values from first principles, thus making the DFT$\textit{+U}$ method a real abinito parameter free approach. Our successful benchmarking studies of the parameter-free DFT$\textit{+U}$ method, for prediction of the structures and the reaction enthalpies of actinide- and lanthanide bearing molecular compounds and solids indicate, that the linear response method (cLDA) provides a very good, and consistent with the cRPA prediction, estimate of the Hubbard $\textit{U}$ parameter. In particular, we found that the Hubbard $\textit{U}$ parameter value, which describes the strength of the on-site Coulomb repulsion between $\textit{f}$-electrons, depends strongly on the oxidation state of the $\textit{f}$-element, its local bonding environment and crystalline structure of the materials, which has never been considered in such detail before. [...]

Note: RWTH Aachen, Diss., 2016

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Contributing Institute(s):

1. Nukleare Entsorgung und Reaktorsicherheit (IEK-6)

Research Program(s):

1. 161 - Nuclear Waste Management (POF3-161) (POF3-161)
2. HITEC - Helmholtz Interdisciplinary Doctoral Training in Energy and Climate Research (HITEC) (HITEC-20170406) (HITEC-20170406)

Appears in the scientific report 2016

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