Computational Chemistry Commons^™

Discovery Of The Multi-Ion Bridge Intermediate: A Computational Exploration Of The Mechanism For Azomethine Ylide Formation From N-Oxides, Martin J. Neal

Electronic Theses and Dissertations

Density functional theory (DFT) provides a method for calculating the ground-state energies of complex molecular systems through evaluating the electron density instead of the full wave function. When results match either experimental outcomes, calculations with DFT offer a computationally efficient method to help explain chemical phenomena. The transformation of tertiary amine N-oxides to azomethine ylides, a simple route to the precursor for 1,3-dipolar cycloadditions that result in the pyrrolidine scaffolds found in natural products, has received only minimal attention due to concerns that its mechanism includes a highly electrophilic intermediate. Utilizing DFT to model the mechanism of the conversion …

Computational Analysis Of Proton Conductivity Factors In Grotthuss-Style Mechanisms, Brock Dyer

Physics and Astronomy Honors Papers

The mechanism and fundamental molecular properties involved in proton conduction are discussed. Four calculable properties are presented: the proton affinity, binding energy (between protonated and neutral forms), intramolecular tautomerization barrier, and proton hopping barrier. An overview of the computational methods used in this thesis, including an introduction to the many-body Schrödinger equation and Density Functional Theory, as well as a look at Plane-Wave Density Functional Theory and Gaussian-Type Orbital Density Functional Theory are presented. 4,5-dimethyl-[1,2,3]-triazole is used as a model system, with 10 variations being generated with varying amounts and positions of fluorine substitution on the methyl groups. Preliminary calculations …

Structure–Property Relationships Mediated By Lone Pairs And Vacancies In Oxychalcogenides: A Combined Experimental And Theoretical Study, Hoa Hn Nguyen

Chemistry & Biochemistry Dissertations - Archive

Structure–property relationships in some oxychalcogenide materials are strongly governed by the interplay between stereochemically active lone pairs and anion vacancy formation. Through a combination of density functional theory (DFT), synchrotron and neutron total scattering and optical characterization, this work elucidates how local symmetry breaking, chemical substitution, and vacancy dynamics influence electronic and optical behavior across several lone pair-containing systems. In crystalline TeO₂, all three polymorphs exhibit wide band gaps with Te⁴⁺ 5s² lone pairs contributing significantly near the valence band edge. Oxygen vacancy formation is thermodynamically favorable and induces asymmetric charge redistribution and enhanced polarizability, supporting …

Towards Automating The Study And Discovery Of Electroactive Π-Conjugated Molecules, Rebekah Ann Duke-Crockett

Theses and Dissertations--Chemistry

Chemistry is entering a new paradigm of automation and data-driven discovery. Automated discovery is grounded in well-curated “big data.” As generative and predictive models fueled by simulation data see growing success, emerging robotic automation enables the generation of unprecedented volumes of experimental data. Automation-powered, data-driven approaches hold tremendous potential for groundbreaking insights and innovations, particularly in the study and discovery of electroactive π-conjugated molecules. Realizing this potential, however, requires democratizing chemical data and the automation needed to generate and use it. There is a need to expand access to the tools for findable, accessible, interoperable, and reusable (FAIR) data management …

Nuclear Fuel Cycle Chemistry: A Density Functional Study, Eduardo Montoya

UNLV Theses, Dissertations, Professional Papers, and Capstones

The nuclear fuel cycle aptly describes the life cycle of nuclear fuel sources such as uranium. From its early forms in naturally bearing ores, to its high-temperature sintering into a fuel pellet, the chemistry uranium experiences throughout the fuel cycle is diverse, driving many experimental efforts towards understanding its chemistry to both improve nuclear technologies and advance the safety and handling of nuclear materials. Computing techniques and methodologies can be used to supplement experimental research and are readily available to researchers interested in utilizing computing-based data to support experimental findings. Density functional theory (DFT) is commonly practiced, reliably predicting the …

Modelling Terrestrial And Potential Extraterrestrial Photopigments Via Density Functional Theory, Dorothea Illner

Theses and Dissertations

In the search for extraterrestrial life, biosignatures play a crucial role in identifying its putative traces. A commonly known and robust biosignature is the Vegetation Red Edge (VRE), which can be described as a sharp increase of reflectance observed from a planet and stems from the light absorption of photopigments in specific regions in the electromagnetic spectrum. For Earth, this VRE is known to occur around 700 nm, however, if the photopigments absorb light in different regions and have different structures the VRE could experience a wavelenght shift.

In this work, Chlorophyll a and a potential photopigment precursor called Phot0 …

Mechanistic Investigation Of C—C Bond Activation Of Phosphaalkynes With Pt(0) Complexes, Roberto M. Escobar, Abdurrahman C. Ateşin, Christian Müller, William D. Jones, Tülay Ateşin

Research Symposium

Carbon–carbon (C–C) bond activation has gained increased attention as a direct method for the synthesis of pharmaceuticals. Due to the thermodynamic stability and kinetic inaccessibility of the C–C bonds, however, activation of C–C bonds by homogeneous transition-metal catalysts under mild homogeneous conditions is still a challenge. Most of the systems in which the activation occurs either have aromatization or relief of ring strain as the primary driving force. The activation of unstrained C–C bonds of phosphaalkynes does not have this advantage. This study employs Density Functional Theory (DFT) calculations to elucidate Pt(0)-mediated C–CP bond activation mechanisms in phosphaalkynes. Investigating the …

Computational Study Of Proton Transfer At Transition Metal Hydrides, Megan Ford

Honors Theses

Energy storage in the bonds of common chemical feedstocks is an attractive solution to the unreliability of wind and solar power due to its long term efficiency and easy recoverability. Energy is stored by reducing chemicals like ammonia, formic acid, and hydrogen, the reaction of which is dependent on a catalyst. To catalyze the reaction, the catalyst undergoes a slow proton transfer (PT) step to form what is known as a metal hydride. The sluggish kinetics of this step lower the effectiveness of the catalyst, and therefore must be better understood in order to improve the efficiency of energy storage …

A Dft Analysis And Simple Hamiltonian Modeling Of A Molecular System Employed For Experimental Evidence Of Quantum Teleportation, Pedro Ulises Medina Gonzalez

Open Access Theses & Dissertations

Radical ion pairs (RIPs) have been used to demonstrate quantum teleportation in molecular systems for applications in quantum information science. Covalent organic donor-acceptor (D-A) molecules can produce RIPs through photo-induced charge transfer and an additional radical (R) molecule makes quantum teleportation possible. We present the electronic structure and analyze charge transfer excited states of a recently studied [1] D-A-R molecular system using density functional theory. The distances between donor-acceptor and donor-radical are about 12.9 \AA $\,$ and 21.9 \AA, respectively. The excitation energies are calculated using the perturbative delta-SCF method and agree with other conventional excited-state methods and experimental reference …

Translating Chemistry, Structure, And Processing To The Solid-State Morphology And Function Of Organic Semiconductors Through Computational Modeling And Simulations, Chamikara D. Karunasena

Theses and Dissertations--Chemistry

The immense synthetic design space and material versatility have driven the exploration and development of organic semiconductors (OSC) over several decades. While many OSC designs focus on the chemistries of the molecular or polymer building blocks, a priori, multiscale control over the solid-state morphology is required for effective application of the active layer in a given technology. However, molecular assembly during solid-state formation is a complex function interconnecting the building block chemistry and the processing environment. Insufficient knowledge as to how these aspects engage, especially at the atomistic and molecular scales, has so far limited the ability to predict …

Developing And Deploying Data-Driven Tools For Accelerated Design Of Organic Semiconductors, Vinayak Bhat

Theses and Dissertations--Chemistry

Organic semiconductors have gained widespread attention due to their potential applications in flexible, low-cost, lightweight electronics, energy storage and generation technologies, and sensing applications. However, developing new organic semiconductors with improved performance remains a significant challenge due to the vast chemical space of possible molecular and materials structures. Furthermore, the high cost and time-consuming nature of experimental synthesis and characterization hinder the rapid discovery of new materials. To overcome these challenges, this dissertation presents a data-driven approach to organic semiconductor discovery. The primary focus of this work is the development of data-driven tools, namely machine learning models, to predict critical …

First Principles Calculations To Investigate Surface And Catalytic Properties Of Materials For Green Energy Generation, Keerthan Raghavendra Rao

Theses and Dissertations--Chemistry

Climate change due to greenhouse gas build up in the earth’s atmosphere is an existential threat to humanity. To mitigate climate change, a significant shift from fossil fuels is necessary. Over the years, several renewable energy sources like solar, wind, geothermal etc. have been explored with the aim providing carbon-free energy. In this work, we focus on using density functional theory (DFT) methods to investigate key functional properties of materials of interest for applications in solar cells and catalytic conversion for energy generation. We show geometric effects of carboxylic acid binding on a transition metal surface to impact the deoxygenation …

Evaluation Of The Energetic Factors In Crystalline Pharmaceuticals Using Solid-State Density Functional Theory And Low-Frequency Vibrational Spectroscopy, Margaret P. Davis

Dissertations - ALL

Due to the importance of maintaining stable and effective pharmaceutical solid doses, it is critical to study the variety of solid forms that active pharmaceutical ingredients can adopt including polymorphs, hydrates, and cocrystals. In this work, low-frequency vibrational spectroscopies and rigorous quantum mechanical simulations are combined to provide a new technique for characterizing and investigating pharmaceutically relevant polymorphs, hydrates, and cocrystals as well as a series of model cocrystals. Low-frequency spectra in the sub-200 cm-1 range provide not only unique and characteristic spectra for all of the systems explored here but, along with X-ray structural parameters, they offer a way …

Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva

Dissertations, Master's Theses and Master's Reports

The field of two-dimensional (2D) layered materials provides a new platform for studying diverse physical phenomena that are scientifically interesting and relevant for technological applications. Theoretical predictions from atomically resolved computational simulations of 2D materials play a pivotal role in designing and advancing these developments. The focus of this thesis is 2D materials especially graphene and BN studied using density functional theory (DFT) and molecular dynamics (MD) simulations. In the first half of the thesis, the electronic structure and optical properties are discussed for graphene, antimonene, and borophene. It is found that the absorbance in (atomically flat) multilayer antimonene (group …

From Evaluating The Performance Of Approximations In Density Functional Theory To A Machine Learning Design, Pedram Tavazohi

Graduate Theses, Dissertations, and Problem Reports (ETD)

Density-functional theory (DFT) has gained popularity because of its ability to predict the properties of a large group of materials a priori. Even though DFT is exact, there are inaccuracies introduced into the theory due to the approximations in the exchange-correlation (XC) functionals. Over the 50 years of its existence, scientists have tried to improve the design of the XC functionals. The errors introduced by these functionals are not consistent across all types of solid-state materials. In this project, a high throughput framework was utilized to compare the theoretical DFT predictions with the experimental results available in the Inorganic Crystal …