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Tethered Axial Coordination As A Control Modality In Rhodium(Ii)-Catalyzed Carbene Transfer Reactions, Anthony Dean Abshire
Tethered Axial Coordination As A Control Modality In Rhodium(Ii)-Catalyzed Carbene Transfer Reactions, Anthony Dean Abshire
Doctoral Dissertations
Rhodium(II) paddlewheels are versatile carbene transfer catalyst that are broadly applied in insertion reactions, cycloadditions, and ylide transformations. The effects of axial coordination in rhodium(II)-catalyzed carbene transfer reactions are still little understood due to compounding factors that are difficult to isolate. Traditionally, researchers study axial coordination by addition of Lewis base additives. To ensure interaction between the Lewis base and catalyst, high molar equivalents are used. This can also have the undesired effect of hampering the activity of the catalyst and suppressing the yield of the reaction. We have developed ligands with a tethered Lewis base to overcome these issues. …
Rational Design Of Non-Noble Metal Intermetallic Compounds With Tunable Surface And Catalytic Chemistry Via Combined Computational And Experimental Method, Yuanjun Song
Doctoral Dissertations
This study focuses upon understanding and rationally tuning the surface reactivity towards C, H, and O of non-noble metal intermetallic compounds (IMCs) catalysts in olefin production and hydrocarbons reforming reactions. In these reactions, different degrees of surface reactivity towards C, H, and O are required to achieve high activity and selectivity as well as stability. A combined computational and experimental method was performed to build this understanding how to rationally design catalysts. Investigations based on quantum chemical calculations indicate surface reactivity towards C, H, and O is a function of element size of constituent elements as well as bulk and …
Theoretical Modeling Of Metallic Compounds With Versatile Properties By Combining First-Principles Calculations And Global Structure Prediction Algorithms, Jinseon Park
Doctoral Dissertations
Improving the target properties of existing materials or finding new materials with enhanced functionality for practical applications is at the heart of the materials research. In this respect, the first-principles approaches, which have been successfully integrated into modern high- performance computers, have become an indispensable part of the materials research, providing a better understanding of existing materials and guidance on the design of new materials. Using state-of-the-art computational/theoretical approaches that couple global structure prediction with ab initio density functional theory calculations, we investigate structural and electronic properties of CsxO [cesium oxides], Li1+xMn2O4 [lithium …
Computational Simulations In Materials For Energy Applications 1. Crystal And Electronic Structure In Ln-U-O Compounds. 2. Dynamics Of Point Defect Interaction With Dislocations In Bcc Iron., Luis Alberto Casillas Trujillo
Computational Simulations In Materials For Energy Applications 1. Crystal And Electronic Structure In Ln-U-O Compounds. 2. Dynamics Of Point Defect Interaction With Dislocations In Bcc Iron., Luis Alberto Casillas Trujillo
Doctoral Dissertations
Nuclear energy is a viable solution to the world’s energy demands. Nuclear energy applications involve rich and complex physics, with high energy events, the incorporation of fission products, and the production of point and extended defects. All these phenomena have an impact on the microstructure of the constituent materials and represent efficiency and safety concerns. A mature understanding of the microstructural evolution of the component materials in the nuclear reactor core is essential to have a safe and reliable process. Experimental investigation of materials in radiation environments is difficult and expensive, making computational simulations a suitable alternative. In this dissertation, …
Low Energy Recoil Simulations In Mgo, Linbo3, And Litao3 Using Ab Initio Molecular Dynamics, Benjamin Aaron Petersen
Low Energy Recoil Simulations In Mgo, Linbo3, And Litao3 Using Ab Initio Molecular Dynamics, Benjamin Aaron Petersen
Doctoral Dissertations
Ab initio molecular dynamics (AIMD) was utilized to test a series of materials, MgO, LiNbO3 , and LiTaO3 , to determine defect structures produced due to low energy recoil events . The kinetic energy required to displace an atom from its lattice site, the threshold displacement energy, was calculated for an array of directions in each material, based on symmetry and complexity of the structure. MgO having a simple rock salt structure provided a model material for demonstrating computational techniques used later on LiTaO3 and LiNbO3 . The minimum values for displacing an atom were at …
Investigating The Properties Of Superfluid He-4 Through Density Functional Calculations, Matthew Francis Dutra
Investigating The Properties Of Superfluid He-4 Through Density Functional Calculations, Matthew Francis Dutra
Doctoral Dissertations
We present a study of isotopically pure He-4 systems evaluated using helium density functional theory (He-DFT) with the intent of better understanding their ground state structural and energetic properties, particularly within the scope of singularly-doped helium droplets. We self-consistently solve for the density profiles and chemical potentials for a wide range of pure helium droplet sizes (up to 9500 atoms) via an imaginary time propagation method, and fit the resultant energetic data to a power law formula to be able to extrapolate values for even larger droplets. Subsequent calculations on singularly-doped droplets within the same size range yield accurate binding …
A Study Of The Optical And Negative Ion Properties Of Selected Chiral Molecules, Jason Michael Lambert
A Study Of The Optical And Negative Ion Properties Of Selected Chiral Molecules, Jason Michael Lambert
Doctoral Dissertations
Chirality is subtle geometric property where objects lack reflection plane symmetry. In this thesis I study three chiral molecules using a combination of experimental and theoretical methods to elucidate the relationships between conformation freedom, solvent choice, and temperature. The importance of nuclear motion when predicting the optical rotation is explored. For carvone, corrections with each nuclear mode coordinate is important. Predictions of the ORD have the incorrect sign without the inclusion of vibrational corrections. For the case of two newly synthesized amino acid derivatives the vibrational corrections did not correct the sign of the calculated ORD to bring it into …
Microscopic Description Of Nuclear Fission At Finite Temperature, Jordan David Mcdonnell
Microscopic Description Of Nuclear Fission At Finite Temperature, Jordan David Mcdonnell
Doctoral Dissertations
While a predictive, microscopic theory of nuclear fission has been elusive, advances in computational techniques and in our understanding of nuclear structure are allowing us to make significant progress. Through nuclear energy density functional theory, we study the fission of thorium and uranium isotopes in detail. These nuclides have been thought to possess hyperdeformed isomers in the third minima of their potential energy surfaces, but microscopic theories tend to estimate either shallow or non- existent third minima in these nuclei. We seek an explanation in terms of neutron shell effects. We study how the fission pathways, the symmetry, and the …