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Thermodynamic Properties of Quinoxaline-1,4-Dioxide Derivatives: A Combined Experimental and Computational Study

Description: Article on thermodynamic properties of quinoxaline-1,4-dioxide derivatives and a combined experimental and computational study.
Date: March 16, 2004
Creator: Silva, Maria D. M. C. Ribeiro da; Gomes, José R. B.; Gonçalves, Jorge M.; Sousa, Emanuel A.; Pandey, Siddharth & Acree, William E. (William Eugene)
Partner: UNT College of Arts and Sciences

Carbon-Oxygen Bond Formation via Organometallic Baeyer-Villiger Transformations: A Computational Study on the Impact of Metal Identity

Description: Article discussing a computational study on the impact of metal identity and carbon-oxygen bond formation via organometallic Baeyer-Villiger transformations.
Date: December 20, 2011
Creator: Figg, Travis M.; Webb, Joanna R.; Cundari, Thomas R., 1964- & Gunnoe, T. Brent
Partner: UNT College of Arts and Sciences

Thermochemical and Theoretical Studies of Dimethylpyridine-2,6-dicarboxylate and Pyridine-2,3-, Pyridine-2,5-, and Pyridine-2,6-dicarboxylic Acids

Description: Article discussing thermochemical and theoretical studies of dimethylpyridine-2,6-dicarboxylate and pyridine-2,3-, pyridine-2,5- and pyridine-2,6-dicarboxylic acids.
Date: May 6, 2005
Creator: Matos, M. Agostinha R.; Morais, Victor M. F.; Silva, Maria D. M. C. Ribeiro da; Marques, Marta C. F.; Sousa, Emanuel A.; Castiñeiras, Jorge P. et al.
Partner: UNT College of Arts and Sciences

Bottom-up assembly of metallic germanium

Description: This article demonstrates that free electrons from distinct 2D dopant layers coalesce into a homogeneous 3D conductor using anisotropic quantum interference measurements, atom probe tomography, and density functional theory.
Date: August 10, 2015
Creator: Scappucci, Giordano; Klesse, Wolfgang M.; Yeoh, LaReine A.; Carter, Damien J.; Warschkow, Oliver; Marks, Nigel A. et al.
Partner: UNT College of Engineering

Reformulation of DFT + U as a Pseudohybrid Hubbard Density Funcitonal for Accelerated Materials Discovery

Description: This article introduces ACBN0, a pseudohybrid Hubbard density functional that yields an improved prediction of the band structure of insulators such as transition-metal oxides, with only a negligible increase in computational cost.
Date: January 28, 2015
Creator: Agapito, Luis A.; Curtarolo, Stefano & Buongiorno Nardelli, Marco
Partner: UNT College of Arts and Sciences

Interfacial structures and energetics of the strengthening precipitate phase in creep-resistant Mg-Nd-based alloys

Description: This article discusses the study of two interfaces– {112}β1/{1100}Mg and {111}β1/{1120}Mg– that are commensurate with β1/hcp-Mg orientation relationship via first principles calculations.
Date: January 17, 2017
Creator: Choudhuri, Deep; Banerjee, Rajarshi & Srivilliputhur, Srinivasan
Partner: UNT College of Engineering

Accurate and Reliable Prediction of Energetic and Spectroscopic Properties Via Electronic Structure Methods

Description: Computational chemistry has led to the greater understanding of the molecular world, from the interaction of molecules, to the composition of molecular species and materials. Of the families of computational chemistry approaches available, the main families of electronic structure methods that are capable of accurate and/or reliable predictions of energetic, structural, and spectroscopic properties are ab initio methods and density functional theory (DFT). The focus of this dissertation is to improve the accuracy of predictions and computational efficiency (with respect to memory, disk space, and computer processing time) of some computational chemistry methods, which, in turn, can extend the size of molecule that can be addressed, and, for other methods, DFT, in particular, gain greater insight into which DFT methods are more reliable than others. Much, though not all, of the focus of this dissertation is upon transition metal species – species for which much less method development has been targeted or insight about method performance has been well established. The ab initio approach that has been targeted in this work is the correlation consistent composite approach (ccCA), which has proven to be a robust, ab initio computational method for main group and first row transition metal-containing molecules yielding, on average, accurate thermodynamic properties, i.e., within 1 kcal/mol of experiment for main group species and within 3 kcal/mol of experiment for first row transition metal molecules. In order to make ccCA applicable to systems containing any element from the periodic table, development of the method for second row transition metals and heavier elements, including lower p-block (5p and 6p) elements was pursued. The resulting method, the relativistic pseudopotential variant of ccCA (rp-ccCA), and its application are detailed for second row transition metals and lower p-block elements. Because of the computational cost of ab initio methods, DFT is a popular choice ...
Date: August 2013
Creator: Laury, Marie L.
Partner: UNT Libraries

The Impact of Computational Methods on Transition Metal-containing Species

Description: Quantum chemistry methodologies can be used to address a wide variety of chemical problems. Key to the success of quantum chemistry methodologies, however, is the selection of suitable methodologies for specific problems of interest, which often requires significant assessment. To gauge a number of methodologies, the utility of density functionals (BLYP, B97D, TPSS, M06L, PBE0, B3LYP, M06, and TPSSh) in predicting reaction energetics was examined for model studies of C-O bond activation of methoxyethane and methanol. These species provide excellent representative examples of lignin degradation via C-O bond cleavage. PBE0, which performed better than other considered DFT functionals, was used to investigate late 3d (Fe, Co, and Ni), 4d (Ru, Rh, and Pd), and 5d (Re, Os, and Ir) transition metal atom mediated Cβ -O bond activation of the β–O–4 linkage of lignin. Additionally, the impact of the choice of DFT functionals, basis sets, implicit solvation models, and layered quantum chemical methods (i.e., ONIOM, Our Own N-layered Integrated molecular Orbital and molecular Mechanics) was investigated for the prediction of pKa for a set of Ni-group metal hydrides (M = Ni, Pd, and Pt) in acetonitrile. These investigations have provided insight about the utility of a number of theoretical methods in the computation of thermodynamic properties of transition metal hydrides in solution. As single reference wavefunction methods commonly perform poorly in describing molecular systems that involve bond-breaking and forming or electronic near-degeneracies and are typically best described with computationally costly multireference wavefunction-based methods, it is imperative to a priori analyze the multireference character for molecular systems so that the proper methodology choice is applied. In this work, diagnostic criteria for assessing the multireference character of 4d transition metal-containing molecules was investigated. Four diagnostics were considered in this work, including the weight of the leading configuration of the CASSCF wavefunction, C02; T1, ...
Date: December 2015
Creator: Wang, Jiaqi
Partner: UNT Libraries

Systematic Approaches to Predictive Computational Chemistry using the Correlation Consistent Basis Sets

Description: The development of the correlation consistent basis sets, cc-pVnZ (where n = D, T, Q, etc.) have allowed for the systematic elucidation of the intrinsic accuracy of ab initio quantum chemical methods. In density functional theory (DFT), where the cc-pVnZ basis sets are not necessarily optimal in their current form, the elucidation of the intrinsic accuracy of DFT methods cannot always be accomplished. This dissertation outlines investigations into the basis set requirements for DFT and how the intrinsic accuracy of DFT methods may be determined with a prescription involving recontraction of the cc-pVnZ basis sets for specific density functionals. Next, the development and benchmarks of a set of cc-pVnZ basis sets designed for the s-block atoms lithium, beryllium, sodium, and magnesium are presented. Computed atomic and molecular properties agree well with reliable experimental data, demonstrating the accuracy of these new s-block basis sets. In addition to the development of cc-pVnZ basis sets, the development of a new, efficient formulism of the correlation consistent Composite Approach (ccCA) using the resolution of the identity (RI) approximation is employed. The new formulism, denoted 'RI-ccCA,' has marked efficiency in terms of computational time and storage, compared with the ccCA formulism, without the introduction of significant error. Finally, this dissertation reports three separate investigations of the properties of FOOF-like, germanium arsenide, and silicon hydride/halide molecules using high accuracy ab initio methods and the cc-pVnZ basis sets.
Date: May 2009
Creator: Prascher, Brian P.
Partner: UNT Libraries

Performance of Density Functional Theory for 3d Transition Metal-Containing Complexes: Utilization of the Correlation Consistent Basis Sets

Description: Article discussing the performance of density functional theory for 3d transition metal-containing complexes and the utilization of the correlation consistent basis sets.
Date: July 2, 2009
Creator: Tekarli, Sammer M.; Drummond, Michael L.; Williams, T. Gavin; Cundari, Thomas R., 1964- & Wilson, Angela K.
Partner: UNT College of Arts and Sciences

Activation of Carbon-Hydrogen and Hydrogen-Hydrogen Bonds by Copper-Nitrenes: A Comparison of Density Functionality Theory with Single- and Multireference Correlation Consistent Composite Approaches

Description: Article on a comparison of density functional theory with single- and multireference correlation consistent composite approaches (ccCA).
Date: October 19, 2009
Creator: Tekarli, Sammer M.; Williams, T. Gavin & Cundari, Thomas R., 1964-
Partner: UNT College of Arts and Sciences

Unusual Electronic Features and Reactivity of the Dipyridylazaallyl Ligand: Characterizations of (smif)2M [M = Fe, Co, Co+, Ni; smif = {(2-py)CH}2N] and [(TMS)2NFe]2(smif)2

Description: Article discussing unusual electronic features and reactivity of the dipyridylazaallyl ligand and characterizations of (smif)2M [M = Fe, Co, Co+, Ni; smif = {(2-py)CH}2N and [(TMS)2NFe] 2(smif)2.
Date: February 19, 2009
Creator: Frazier, Brenda A.; Wolczanski, Peter T.; Lobkovsky, Emil B. & Cundari, Thomas R., 1964-
Partner: UNT College of Arts and Sciences

Chiral Steering of Molecular Organization in the Limit of Weak Adsorbate-Substrate Interactions: Enantiopure and Racemic Tartaric Acid Domains on Ag(111)

Description: Article on the chiral steering of molecular organization in the limit of weak adsorbate-substrate interactions.
Date: April 23, 2010
Creator: Santagata, Nancy M.; Lakhani, Amit M.; Davis, Bryce F.; Luo, Pengshun; Buongiorno Nardelli, Marco & Pearl, Thomas P.
Partner: UNT College of Arts and Sciences