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Showing 1 to 20 of 82 for “"density functional theory calculations"”.
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Density functional theory calculations on materials in photocatalysis
… friendly. In this thesis, we report density functional theory (DFT) calculations on several promising semiconductor materials used in photocatalytic water splitting aiming to achieve a better understanding on a theoretical level. In chapter 3, we report extensive DFT calculations on …
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Vibrational spectroscopy and density functional theory calculations, a powerful approach for the characterization of pharmaceuticals and new organometallic complexes
… spectroscopy in conjunction with accurate density functional theory (DFT) calculations, are presented. The DFT computed molecular geometries of the species of interest reproduced the crystal structure data very well and in conjunction with IR and Raman measurements helped us to clarify the …
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Density Functional Theory Calculations Complement Mass Spectrometry Experiments in the Investigation of Biomass Fast Pyrolysis and Ion-Molecule Reaction Mechanisms
Biomass fast-pyrolysis, or the rapid heating in the absence of oxygen, is a promising method for biomass conversion necessary for a renewable energy economy. Although kinetic models of cellulose pyrolysis have existed since the 1970s, current models and hypothesized reaction networks fail to …
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Exploration of basis set issues for calculation of intermolecular interactions and density functional theory calculations of vanadium oxide clusters and their reactions with sulfur dioxide
… related to the choice of a basis set for these calculations, in particular size of the basis set, efficiency of 2-electron integral codes, basis set superposition error (BSSE), and the linear dependence of basis functions. In an attempt to find more efficient basis sets for calculations of …
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A multiscale model for the oxide ion conducting and proton conducting solid oxide cells
… Here, we develop a multiscale model combining density functional theory calculations, transition state theory and continuum modeling to elucidate the essential reaction steps and predict the performance of the device. Density functional theory calculations are used to obtain the free energy …
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Insights into formation of semiconductor nanocrystals : from first principles calculations to kinetic models of nucleation and growth
… this challenge by utilizing first principles calculations and mathematical modeling to study the formation of cadmium selenide nanocrystals, the most frequently studied and best characterized nanocrystal system. In the first part of this thesis we investigate the elementary reaction steps that …
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Mechanisms of the Wurtzite to Rock Salt Phase Transitions in Galium Nitride
… for this transition. We then used FIREBALL to do density functional theory calculations and found enthalpy barrier heights for the transition pathway. We used this to determine the mechanisms that are the most favorable for GaN. The most favorable mechanisms for GaN are those that break no bonds …
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Studies of the Structure and Electrocatalytic Reduction of Oxygen on Modified Electrode Surfaces
… in basic media is examined using SERS and density functional theory calculations. The spectroscopy reveals superoxide species as a reduction intermediate, while no peroxide is detected. The spectroscopy also shows the presence of superoxide after the addition of hydrogen peroxide. The …
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Formation and dynamics of defects in pure and ion implanted a-titanium studied by quantum simulations
Density-functional theory calculations have been performed to study energetics of defects formation and diffusion in pure and krypton implanted hexagonal closed-packed (h.c.p) titanium. We employed the ab initio electronic structure calculations to study the formation energies of Ti vacancies and …
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Organic reactions catalyzed by copper(I) hydride complexes
… exhibit excellent diastereoselectivity and broad functional-group tolerance. Good enantioselectivity can also be achieved in the linear-selective reaction. Finally, a mechanistic model for the regiodivergence is proposed on the basis of density functional theory calculations. Chapter 3. …
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Synthesis and Characterization of Methylammonium Strontium Bromide Hybrid Perovskite
… band gap of 4.52 eV which is corroborated by density functional theory calculations. Taken together, these results indicate that the synthesized MASrBr3 perovskite is viable for future high-bandgap device applications.
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Metalloid aluminum clusters with fluorine
Metals have a very high energy density compared to explosives, but typically release this energy slowly via diffusion-limited combustion. There is recent interest in using molecular-scale metalloid clusters as a way to achieve very rapid rates of metal combustion. These clusters contain a mixture …
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Nano-imaging to Determine the Interstitial Nature of Mn(II) Doping in 2D Halide Perovskites
… track the local strain and chemical composition. Density functional theory calculations predict that Mn2+ atoms reside at the interstitial sites between two octahedra in the triangle formed by one Cl- and two I- atoms, which results in a locally expanded structure. These measurements shed light on …
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Oxygen diffusion through titanium and other HCP metals
… alloys, due to their high tensile strength, low density, and excellent corrosion resistance, have great potential in aerospace and medical implant applications. However, Ti alloy properties are very sensitive to oxygen content and readily oxidizes at high temperatures. Ab initio density …
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The c33 elastic constant of MoS2 as a function of pressure and the deposition of multilayer thin films by sputtering
… constants were similar those predicted by hybrid density functional theory calculations by Peelaers and Van de Walle, but lower than those calculated from lattice constant measurements by Fan. However, due to the failure of the Lorentz-Lorenz relationship between index of refraction n and density, …
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Effects of Electron-Vibron Coupling in Single-Molecule Magnet Transport Junctions Using a Hybrid Density Functional Theory and Model Hamiltonian Approach
… on transport through SMMs that utilizes both density functional theory calculations and model Hamiltonian construction and analysis, and to present a software framework based on this hybrid approach for the simulation of transport across user-defined SMMs. The results of these simulations will …
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Computational Modeling of Catalytic Mechanisms of Glycyl Radical Enzymes
… by combining continuum electrostatic and density functional theory calculations. A mechanism for the dehydration of glycerol is proposed that does not involve a complex intramolecular 1→2 shift of the middle hydroxyl group, as previously suggested. Instead, the enzyme uses a pair of …
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Investigation of the interaction of water with the calcite {1014} surface using ab-initio simulation
Density functional theory calculations were employed to explore the interaction between water and the {1014} surface of calcite. In addition a defective {1014} surface and stepped surfaces in contact with water were investigated. A series of percentage water coverages and water con�figurations were …
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Evaluation of Thermal Effects and Lattice Vibrations in Molecular Crystals
… work is complemented with solid-state density functional theory calculations, enabling for the evaluation of the energetics of the studied systems, providing insight into the relative stabilities of the studied systems over a range of temperatures, and can even elucidate the mechanisms …
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Ion mobility and mass spectrometric investigations of organophosphates related to chemical warfare agents and pesticides
… of DMEP have unusual fragmentations, and density functional theory calculations are used to aid in the interpretation of the mechanisms involved in these fragmentations. Of note, it is shown that entropy must be taken into consideration, and hence the free energy of the final transition …
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