Development and Efficient Implementation of Electron-Hole Interaction Kernel for Investigation of Electronic Excitations in Semiconductor and Metallic Nanoparticles

The focus of this work is to construct theoretical methods or approaches to tackle computationally challenging problems in quantum chemistry. The primary topic of the work will focus on efficient theories that allow for capturing electron-correlation in semiconductor or metallic nanoparticles. These systems are computationally challenging due to the size of the systems, the number of electrons per atom, and the degeneracy of the particle-hole states. Three methods presented here are aimed at providing novel theoretical methods towards computationally inexpensive electronic excited state calculations. The frequency-dependent geminal-screened electron-hole interaction kernel (FD-GSIK) method provides a real-space approach towards eliminating the virtual space reducing the computational effort present in most excited state methods. Dressed molecular orbital basis is presented to compress the configuration space in metallic nanoparticles, resulting in a cheap multi-reference approach to obtaining electron-correlation. Finally, the moment generated molecular orbital basis is derived to provide an alternative approach that utilizes moments of the reference function to decouple particle and hole states. A secondary focus within this work is to provide efficient Monte Carlo sampling techniques for modeling and integration. Monte Carlo provides an efficient pathway to sampling experimental models and evaluation of complicated integrals which are normally computationally costly. The theoretical developments presented in this work allow for understanding theoretical properties in semiconductor or metallic nanoparticles which normally would be computationally prohibited

The Load-Carrying Characteristics of a Bituminous Concrete Resurfacing Mixture

Abstract not availabl

Effects of welding conditions fna microstructure on the notch toughness of multiple-pass welds

The beneficial and harmful effects on the notch toughness of weld metal resulting from reheating during multiple-pass welding have been investigated

Dearomative Spirocyclizations for the Preparation of Complex Carbo- and Heterocycles and the Development of a Thermodynamic Diastereomer Enrichment of a Fluorophosphite Ligand

I. Enantioselective Phenolic α-Oxidation Using H2O2 via an Unusual Double Dearomatization Mechanism We describe the oxidative dearomatizations of salicyl alcohols via their derived bis(dichloroacetates) using hydrogen peroxide as a mild oxidant that intercepts a transient ortho-quinone methide. A stereochemical study revealed that the reaction proceeds via a new mechanism relative to other phenol dearomatizations and is complementary to extant methods that rely on hypervalent iodine. Using a new chiral phase-transfer catalyst, the first asymmetric syntheses of ortho-spiroepoxydienones were reported. The synthetic utility of the derived products is demonstrated in a downstream complexity-generating transformation. II. Phenolic Oxidation Using H2O2 via in Situ Generated para-Quinone Methides for the Preparation of para-Spiroepoxydienones We report an efficient preparation of dearomatized 1-oxaspiro[2.5]octa-4,7-dien-6-ones (para-spiroepoxydienones) via the nucleophilic epoxidation of in situ generated para-quinone methides from 4-(hydroxymethyl)phenols using hydrogen peroxide. The developed protocol bypasses the need for stoichiometric bismuth reagents or diazomethane that are frequently deployed for p-spiroepoxydienone preparation. The unusual reactivity of p-spiroepoxydienones is further explored in numerous downstream complexity-building transformations. III. N-Heterospirocyclic Dienone Scaffolds via a One-Pot, Dearomative ortho-Semidine Rearrangement/Imine Hydrolysis We have developed a one-pot, dearomative ortho-semidine rearrangement of tetrahydrodizocines and subsequent imine hydrolysis to afford synthetically useful dienone scaffolds with a heterospirocyclic tetrahydroisoquinoline moiety. These N-spirodienone scaffolds are used as linchpins for generation of downstream heterocyclic scaffolds via utilization of the spirocyclic nitrogen as a directing group. IV. The Development of a Thermodynamic Diastereomer Enrichment of a Fluorophosphite Ligand We describe the development a thermodynamic diastereomer enrichment of a fluorophosphite ligand that exists as an initial 1:1 mixture of diastereomers. Using a fluoride source, the two diastereomers were readily interconverted. A solvent screen identified cyclohexanone as a privileged solvent for favoring formation of the anti isomer in ratios up to 5:1 dr at low temperatures. Reaction optimization and product isolation techniques were performed for applicability to process scale-up. This work was conducted in collaboration with Eastman Chemical Company.Doctor of Philosoph

Thermospheric density variations: Observability using precision satellite orbits and effects on orbit propagation

This is the published version. Copyright 2013 American Geophysical Union.This paper examines atmospheric density estimated using precision orbit ephemerides (POE) from the CHAMP and GRACE satellites during short periods of greater atmospheric density variability. The results of the calibration of CHAMP densities derived using POEs with those derived using accelerometers are examined for three different types of density perturbations, [traveling atmospheric disturbances (TADs), geomagnetic cusp phenomena, and midnight density maxima] in order to determine the temporal resolution of POE solutions. In addition, the densities are compared to High-Accuracy Satellite Drag Model (HASDM) densities to compare temporal resolution for both types of corrections. The resolution for these models of thermospheric density was found to be inadequate to sufficiently characterize the short-term density variations examined here. Also examined in this paper is the effect of differing density estimation schemes by propagating an initial orbit state forward in time and examining induced errors. The propagated POE-derived densities incurred errors of a smaller magnitude than the empirical models and errors on the same scale or better than those incurred using the HASDM model