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Multi-Reference Systems In Chemistry; Unconventional Bonding In Organic Chemistry; Covalent Bonding In Transition Metal Clusters, Alan Wilfred Humason 2018 Southern Methodist University

Multi-Reference Systems In Chemistry; Unconventional Bonding In Organic Chemistry; Covalent Bonding In Transition Metal Clusters, Alan Wilfred Humason

Chemistry Theses and Dissertations

The geometries, chemical properties, and reactivities of molecules are determined by their electronic structure. The field of ab initio computational chemistry works to calculate the kinetic and potential energies between the nuclei and electrons of a molecule. These calculations usually begin with the determination the electronic ground state.

Molecules that cannot be adequately described with a single, ground state configuration are called \textit{multi-reference systems}, which require the calculation of a linear combination of all pertinent electronic configurations, with a corresponding increase in computational cost. This is not `black box' methodology, because solving these systems requires a good understanding of ...


Modeling Adsorption And Diffusion Of Atomic Oxygen On The Ag(111) Surface Using Kinetic Monte Carlo Simulations, Seth Spencer Street, Sharani Roy, Sara Isbill 2018 University of Tennessee, Knoxville

Modeling Adsorption And Diffusion Of Atomic Oxygen On The Ag(111) Surface Using Kinetic Monte Carlo Simulations, Seth Spencer Street, Sharani Roy, Sara Isbill

EURēCA: Exhibition of Undergraduate Research and Creative Achievement

Oxidized silver surfaces are widely used as industrial heterogeneous catalysts to oxidize small organic compounds, such as ethylene. While surface-adsorbed oxygen is known to participate in catalysis, it has been suggested that ‘subsurface’ oxygen adsorbed in the near-surface region of silver also plays important roles in surface reconstruction and reactivity. However, the formation, motion, and chemical behavior of subsurface oxygen in silver are not well understood. In the present work, a kinetic Monte Carlo (KMC) simulation has been developed using the Python programming language to computationally model the diffusion kinetics of atomic oxygen (AO) at the Ag(111) surface. This ...


Errata For Manuscript #34, Carl W. David, Jan Siroky 2018 University of Connecticut

Errata For Manuscript #34, Carl W. David, Jan Siroky

Chemistry Education Materials

An error in manuscript 34 of this collection concerning the Laplacian in spherical polar coordinates is corrected.


Computational And Analytical Modelling Of Droplet-Macroion Interactions, Myong In Oh 2018 The University of Western Ontario

Computational And Analytical Modelling Of Droplet-Macroion Interactions, Myong In Oh

Electronic Thesis and Dissertation Repository

Charged droplets involving macromolecules undergo distinct disintegration mechanisms and shape deformations as a consequence of droplet-macroion interactions. Three general classes of droplet-macroion interactions that have been identified in the Consta group are: contiguous extrusion of a linear macroion from a droplet, "pearl-necklace" droplet conformations, and "star"-shaped droplets. This dissertation probes in a systematic manner the onset and various outcomes of macroion-droplet interactions, using atomistic molecular dynamics and realistic examples of solvent and macromolecules.

When the charge-squared-to-volume ratio of a droplet is below but near a threshold value, certain flexible macromolecules, such as poly(ethylene glycol), extrude from a droplet ...


Reduction Of The Ordered Magnetic Moment And Its Relationship To Kondo Coherence In, Benjamin G. Ueland, Na Hyun Jo, Aashish Sapkota, W. Tian, Morgan W. Masters, Halyna Hodovanets, Savannah S. Downing, Connor Schmidt, Robert McQueeney, Sergey L. Bud’ko, Andreas Kreyssig, Paul C. Canfield, Alan Goldman 2018 Iowa State University and Ames Laboratory

Reduction Of The Ordered Magnetic Moment And Its Relationship To Kondo Coherence In, Benjamin G. Ueland, Na Hyun Jo, Aashish Sapkota, W. Tian, Morgan W. Masters, Halyna Hodovanets, Savannah S. Downing, Connor Schmidt, Robert Mcqueeney, Sergey L. Bud’Ko, Andreas Kreyssig, Paul C. Canfield, Alan Goldman

Ames Laboratory Accepted Manuscripts

The microscopic details of the suppression of antiferromagnetic order in the Kondo-lattice series Ce1-&ITx&ITLa&ITx&ITCu2Ge2 due to nonmagnetic dilution by La are revealed through neutron diffraction results for x = 0.20, 0.40, 0.75, and 0.85. Magnetic Bragg peaks are found for 0.20 <= x <= 0.75, and both the Ned temperature T-N and the ordered magnetic moment per Ce mu linearly decrease with increasing x. The reduction in mu points to strong hybridization of the increasingly diluted Ce 4f electrons, and we find a remarkable quadratic dependence of mu on the Kondo-coherence temperature. We discuss our results in terms of local-moment- versus itinerant-type magnetism and mean-field theory and show that Ce1-&ITx&ITLa&ITx&ITCu2Ge2 provides an exceptional opportunity to quantitatively study the multiple magnetic interactions in a Kondo lattice.


Quantum Roaming Dynamics On Model Double Morse And Ion-Molecule Potentials, Luke O'Connor 2018 La Salle University

Quantum Roaming Dynamics On Model Double Morse And Ion-Molecule Potentials, Luke O'Connor

HON499 projects

The quantum dynamics on a pair of model two dimensional potential energy surfaces is studied using time-independent and wave packet analyses. The first potential is a reduced dimensional model of an ion-dipole reaction and the second is a planar double Morse potential. Both potentials have been of recent interest in characterizing the roaming reaction mechanism using classical dynamics. Roaming resonance states related to the classically observed roaming dynamics are isolated, and quantum signatures of roaming on these potentials are discussed. The effects of the shape of the double Morse potential on the quantum dynamics are also considered.


Electrochemical And Corrosion Examination Of Copper Under Deep Geologic Conditions For The Application Of Nuclear Waste Containers, Taylor L. Martino 2018 The University of Western Ontario

Electrochemical And Corrosion Examination Of Copper Under Deep Geologic Conditions For The Application Of Nuclear Waste Containers, Taylor L. Martino

Electronic Thesis and Dissertation Repository

Copper is the selected material for the fabrication of nuclear fuel waste containers in Sweden, Finland and Canada due to its corrosion resistance in the anoxic aqueous environments, anticipated in deep geological repositories. A potential oxidant for copper is bisulphide produced either by the dissolution of minerals or by sulphate-reducing bacteria. The primary goals of this thesis were to determine the mechanism of corrosion of copper in bisulphide environments and to investigate the chemistry of the bentonite porewater that will ultimately be in contact with the copper container.

The mechanism of sulphide film growth and the details of copper corrosion ...


Innovative Monte Carlo Methods For Sampling Molecular Conformations, Aliasghar Sepehri 2018 Louisiana State University

Innovative Monte Carlo Methods For Sampling Molecular Conformations, Aliasghar Sepehri

LSU Doctoral Dissertations

Sampling molecular conformations is an important step in evaluating physical, mechanical, hydrodynamic, and optical properties of flexible molecules especially polymers. One powerful method for this purpose is configurational-bias Monte Carlo in which one random segment of a molecule is chosen, all segments toward one random end are removed, and then regrown segment by segment to produce a new geometry to be accepted/rejected according to probability laws. The advantage of this method is the ability to generate acceptable conformations that are favorable for intra- and intermolecular energies to save computational costs. However, when there are several interdependent energetic terms, trial ...


Investigation Of Novel Electrolytes For Use In Lithium-Ion Batteries And Direct Methanol Fuel Cells, Kartik Pilar 2018 The Graduate Center, City University of New York

Investigation Of Novel Electrolytes For Use In Lithium-Ion Batteries And Direct Methanol Fuel Cells, Kartik Pilar

All Dissertations, Theses, and Capstone Projects

Energy storage and conversion plays a critical role in the efficient use of available energy and is crucial for the utilization of renewable energy sources. To achieve maximum efficiency of renewable energy sources, improvements to energy storage materials must be developed. In this work, novel electrolytes for secondary batteries and fuel cells have been studied using nuclear magnetic resonance and high pressure x-ray scattering techniques to form a better understanding of dynamic and structural properties of these materials. Ionic liquids have been studied due to their potential as a safer alternative to organic solvent-based electrolytes in lithium-ion batteries and composite ...


The Van Der Waals Fluid's Liquid Vapor Coexistence Locus, Carl W. David 2018 University of Connecticut

The Van Der Waals Fluid's Liquid Vapor Coexistence Locus, Carl W. David

Chemistry Education Materials

The liquid vapor coexistence locus is plotted from the analytical solution to the Maxwell construction for the van der Waals fluid.


Abnormal Phase Transition Between Two-Dimensional High-Density Liquid Crystal And Low-Density Crystalline Solid Phases, Wenbin Li, Longjuan Kong, Baojie Feng, Huixia Fu, Hui Li, Xiao Cheng Zeng, Kehui Wu, Lan Chen 2018 University of Chinese Academy of Sciences

Abnormal Phase Transition Between Two-Dimensional High-Density Liquid Crystal And Low-Density Crystalline Solid Phases, Wenbin Li, Longjuan Kong, Baojie Feng, Huixia Fu, Hui Li, Xiao Cheng Zeng, Kehui Wu, Lan Chen

Xiao Cheng Zeng Publications

Some two-dimensional liquid systems are theoretically predicted to have an anomalous phase transition due to unique intermolecular interactions, for example the first-order transition between two-dimensional high-density water and low-density amorphous ice. However, it has never been experimentally observed, to the best of our knowledge. Here we report an entropy-driven phase transition between a high-density liquid crystal and low-density crystalline solid, directly observed by scanning tunneling microscope in carbon monoxide adsorbed on Cu(111). Combined with first principle calculations, we find that repulsive dipole–dipole interactions between carbon monoxide molecules lead to unconventional thermodynamics. This finding of unconventional thermodynamics in two-dimensional ...


Spectroscopic Studies Of Gas-Phase Metal Cation Complexes With Alkanes And Ammonia, Muhammad Affawn Ashraf 2018 University of Massachusetts Amherst

Spectroscopic Studies Of Gas-Phase Metal Cation Complexes With Alkanes And Ammonia, Muhammad Affawn Ashraf

Doctoral Dissertations

Understanding the non-covalent interaction between metals and small ligands such as methane and ammonia is of key importance because of their industrial and biological applications. However, these interactions are difficult to study and quantify in the bulk phase due to the interaction with neighboring molecules or atoms. Gas phase spectroscopy of mass-selected clusters is a powerful technique that overcomes this challenge by allowing clusters with known composition to be studied in the gas phase. In this thesis, we investigate the interaction between three types of small molecular ligands with metal and metal cluster ions, and answer questions about their geometries ...


Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski 2018 Wojciech Budzianowski Consulting Services

Call For Abstracts - Resrb 2018, June 18-20, Brussels, Belgium, Wojciech M. Budzianowski

Wojciech Budzianowski

No abstract provided.


Carbon Quantum Dots: Bridging The Gap Between Chemical Structure And Material Properties, Timothy J. Pillar-Little Jr. 2018 University of Kentucky

Carbon Quantum Dots: Bridging The Gap Between Chemical Structure And Material Properties, Timothy J. Pillar-Little Jr.

Theses and Dissertations--Chemistry

Carbon quantum dots (CQDs) are the latest generation of carbon nanomaterials in applications where fullerenes, carbon nanotubes, and graphene are abundantly used. With several attractive properties such as tunable optical property, edge-functionalization, and defect-rich chemical structure, CQDs have the potential to revolutionize optoelectronics, electro- and photocatalysis, and biomedical applications. Chemical modifications through the addition of heteroatoms, chemical reduction, and surface passivation are found to alter the band gap, spectral position, and emission pathways of CQDs. Despite extensive studies, fundamental understanding of structure-property relationship remains unclear due to the inhomogeneity in chemical structure and a complex emission mechanism for CQDs.

This ...


Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd 2018 Virginia Commonwealth University

Experimental Evaluation Of Uranyl Transport Into Mesoporous Silica Gel Using Fluorescence, Brandon M. Dodd

Theses and Dissertations

This research investigated parameters that can affect the use of nanoporous silica gel as a media for accumulating a detectable amount of uranium. The unique fluorescence of the Uranyl (UO22+) ion was used to evaluate the transport kinetics and accumulation within silica gel in a static fluid and under pressure driven flow. The addition of fluid flow decreased the time constant from on the order of an hour to approximately 2s with a very low fluid velocity of 0.36cm/s. The 0.36cm/s fluid velocity was found to be the critical velocity above which there was ...


Computational Study Of Lawesson’S Reagent Mediated Fluorenone Dimerization Forming 9,9’-Bilfuorenylidene, Andrew Jourdan Eckelmann 2018 Missouri State University

Computational Study Of Lawesson’S Reagent Mediated Fluorenone Dimerization Forming 9,9’-Bilfuorenylidene, Andrew Jourdan Eckelmann

MSU Graduate Theses

The ambition of this work is to start a path to the a priori rational design of high yield production for electron acceptors with finely tuned band gaps, from the comfort of an armchair. To this end, organic photovoltaics offer a cheap and sustainable means of manufacture using readily available materials and avoids the toxicity of some of the heavy metals used in first and second-generation solar cells such as cadmium. The microwave assisted Lawesson’s reagent mediated one-pot one-step solventless synthesis takes less than 3 minutes and results in an 84% yield of 9,9’-bifluorenylidene from two equivalents ...


Physicochemical, Spectroscopic Properties, And Diffusion Mechanisms Of Small Hydrocarbon Molecules In Mof-74-Mg/Zn: A Quantum Chemical Investigation, Gemechis Degaga 2018 Michigan Technological University

Physicochemical, Spectroscopic Properties, And Diffusion Mechanisms Of Small Hydrocarbon Molecules In Mof-74-Mg/Zn: A Quantum Chemical Investigation, Gemechis Degaga

Dissertations, Master's Theses and Master's Reports

In petroleum refining industries, the fracturing process allows for the cracking of long-chain hydrocarbons into a mixture of small olefin and paraffin molecules that are then separated via the energetically and monetarily demanding cryogenic distillation process. In an attempt to mitigate both energetic and capital consumptions, selective sorption of light hydrocarbons by tunable sorbents, such as metal-organic frameworks (MOFs), appears to be the most promising alternative for a more efficient gas separation process. MOFs are novel porous materials assembled from inorganic bricks connected by organic linkers. From a crystal engineering stand point, MOFs are advantageous in creating a range of ...


Quantum Chemical Studies Of Noncovalent Interactions And Multicenter Bonds Utilizing Local Vibrational Modes, Vytor Oliveira 2017 Southern Methodist University

Quantum Chemical Studies Of Noncovalent Interactions And Multicenter Bonds Utilizing Local Vibrational Modes, Vytor Oliveira

Chemistry Theses and Dissertations

Noncovalent interactions play an important role for the design of novel drugs, better catalysts, synthesis of complex supramolecular structures, and so on. To develop new materials, a well-founded knowledge of how to control the strength of these interactions is desirable. Despite the many investigations done so far, a quantitative assessment of the intrinsic strength of most types of noncovalent interactions is still missing. Recently and for the first time, the Konkoli-Cremer local modes analysis was successfully used to probe the intrinsic strength of hydrogen and pnicogen bonds. We extended these investigations to more than 300 halogen and chalcogen bonds. A ...


Synthesis, Characterization, And Spectroscopy Of Donor-Acceptor Charge Transfer Complexes, DOMINIC K. KERSI 2017 University of New Mexico

Synthesis, Characterization, And Spectroscopy Of Donor-Acceptor Charge Transfer Complexes, Dominic K. Kersi

Chemistry ETDs

A series of square-planar metal (diimine)(dichalcogenolene) chromophoric complexes have been synthesized, characterized and studied spectroscopically. Studies conducted on diimineplatinum(II) dichalcogenolene complexes (LPtL’) using time resolved spectroscopic techniques such as transient absorption and emission, reveal a charge-separated excited state of the type dichalcogenolene → diimine charge-transfer (LL’CT) [(dichalcogenolene•+)Pt(diimine-) with an open shell donor-acceptor biradical character. Long-live excited state lifetimes were observed for these complexes upon visible photoexcitation of the LL’CT or MMLL’CT band. A direct linear relationship is observed to exist between photoluminescence rates, calculated SOC matrix elements, and 13C-NMR chemical shifts.

A series ...


Study Of 2,5-Diaminoimidazolone, A Mutagenic Product Of Oxidation Of Guanine In Dna, Hannah Catherine J. Pollard 2017 East Tennessee State University

Study Of 2,5-Diaminoimidazolone, A Mutagenic Product Of Oxidation Of Guanine In Dna, Hannah Catherine J. Pollard

Electronic Theses and Dissertations

2,5-diaminoimidazolone (Iz) is an important product of a 4-electron oxidation of guanine. The present research focuses on the mechanisms of formation of Iz via pathways initiated by guanine oxidation by one-electron oxidants (OEOs) generated by X-ray radiolysis in aqueous solutions. The kinetics of formation and yields of Iz in reactions of native highly polymerized DNA with different OEOs have been compared using an HPLC-based quantitative analysis of low-molecular products generated from the reaction of DNA-bound Iz with primary amines. Mechanisms of Iz formation in DNA have been investigated including oxygen and superoxide dependence as well as the hypothesis that ...


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