Dissertation
ACCURATE AB INITIO THERMOCHEMISTRY AND SPECTROSCOPY OF GAS PHASE ACTINIDE-CONTAINING MOLECULES
Doctor of Philosophy (PhD), Washington State University
01/2019
Handle:
https://hdl.handle.net/2376/111430
Abstract
Actinide-containing molecules are difficult to characterize due to both their radioactivity and their multi-determinantal wavefunctions. Highly accurate quantum chemical calculations can be used to circumvent both of these problems, and while it is useful to be able to replicate a previously determined value, it is far more useful to be predictive of chemical properties or to provide newer, more accurate benchmarks to be used in future experiments. This work seeks to provide the most accurate reliable thermochemical and spectroscopic properties of small molecules containing early actinides such as those of thorium and uranium. The Feller-Peterson-Dixon (FPD) composite thermochemistry approach is used calculate reaction enthalpies and fundamental thermodynamic constants. This approach assumes that the total energy of a chemical interaction can be approximated as the sum of individually calculable energy contributions, thus making theoretical determinations more tractable. This work has utilized this approach, with great success, to calculate the ionization potentials (IP) of ThC and ThO and the bond dissociation energies (BDE) of their respective cations. Theoretical results proved to be accurate within the error bars provided by experimental collaborators. ThC+ and ThO+ are products of the reaction of Th+ with CO, so the FPD approach was used to predict the structures, CO binding affinities, IPs, and formation enthalpies of Th(CO)n and Th(CO)n+. A natural bond orbital (NBO) analysis was done to provide insight into the carbonyl back-bonding interaction. Just as important as thermochemistry is spectroscopy. The low-lying electronic state manifolds of ThCl and ThCl+ were determined by calculating potential energy curves at near equilibrium geometries of the first set of excited states as predicted using ligand field theory (LFT). This was used to guide experimental assignments of low energy excited states. This same method was applied to UN, UP, and their cations in addition to using the FPD method to calculate relevant thermochemical constants. Lastly, the methods used above were collectively used to apply the Active Thermochemical Tables (ATcT) method to uranium oxides and halides while being augmented with high accuracy theory. ATcT provides a unique method of calculating thermodynamic constants and connect gas phase calculations to condensed phase chemistry.
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Details
- Title
- ACCURATE AB INITIO THERMOCHEMISTRY AND SPECTROSCOPY OF GAS PHASE ACTINIDE-CONTAINING MOLECULES
- Creators
- Samuel Richard Battey
- Contributors
- Kirk A Peterson (Advisor)James A Brozik (Committee Member)Aurora Clark (Committee Member)Zachariah Heiden (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Department of Chemistry
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Number of pages
- 390
- Identifiers
- 99900581616201842
- Language
- English
- Resource Type
- Dissertation