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Theses/Dissertations

Chemistry

University of Mississippi

Computational

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Full-Text Articles in Physical Sciences and Mathematics

Ab Initio Study Of The Rotation Of The C≡C Group In Benzvalyne, Advait Praveen May 2022

Ab Initio Study Of The Rotation Of The C≡C Group In Benzvalyne, Advait Praveen

Honors Theses

For benzvalyne, we have characterized the minima and transition states of the molecule using the B3LYP, MP2, and M06-2X methods and aug-cc-pVTZ basis set. This was done by calculating the energy of the molecule while rotating the alkyne bond contained within it. After the initial rotation, optimized parameters for the molecule are found. Following this, imaginary frequencies were attempted to be found at the local maximum produced by the graph of the Energy v. rotation angle. Should the negative frequencies be found, the energy of the molecule will be characterized by the CCSD (T) method and aug-cc-pVQZ basis sets. This …


Computational Investigations Into Astrochemical Inorganic Oxides, Ammonia Borane, And Genetic Algorithms, E. Michael Valencia May 2022

Computational Investigations Into Astrochemical Inorganic Oxides, Ammonia Borane, And Genetic Algorithms, E. Michael Valencia

Honors Theses

The formulations of quantum mechanics in the early 1900s were exciting theoretical discoveries, but were not practical to apply until the advent of computers and the subsequent computational methods in 1951. With the introduction of tractable simplifications, procedures such as Hartree-Fock allowed for determination of properties of non-trivial systems. Presently, huge leads of computational power have allowed for extremely precise, quantitative work that can be applied to the human body, synthesis, or even astrochemical processes. This thesis presents works concerning 1) the history of quantum mechanics; 2) a brief primer on computational chemistry and its methods; 3) inorganic oxides in …


A Theoretical Study Of Synchronous Proton Transfer In (Hf)N, (H2O) N, And (Hcl) N Where N = 3, 4, 5, Johnny Yang May 2021

A Theoretical Study Of Synchronous Proton Transfer In (Hf)N, (H2O) N, And (Hcl) N Where N = 3, 4, 5, Johnny Yang

Honors Theses

For (HF)n, (H2O)n, and (HCl)n (n = 3 − 5), we have rigorously characterized the structures for the minima and transition states for synchronous proton transfer (SPT) with the CCSD(T) method and aug-cc-pVTZ basis set. The electronic barrier heights (∆E) associated with these transition states have also been computed with the explicitly correlated CCSD(T)-F12 method and the aug-cc-pVQZ-F12 basis set (abbreviated aQZ-F12). (HCl)n (n = 3 − 5) SPT transition states have not been previously identified to the best of our knowledge, and they have been found …


Spectroscopic Analysis Of Potential Astromolecules Via Quantum Chemical Quartic Force Fields, Mason Gardner May 2021

Spectroscopic Analysis Of Potential Astromolecules Via Quantum Chemical Quartic Force Fields, Mason Gardner

Honors Theses

Astrochemistry has been substantially aided by computational techniques, particularly through the use of Quartic Force Field (QFF) analysis. Several methods have proven useful at correlating computed spectroscopic data with experimental observations. The F12-TZ QFF correlated well with experimental data for silicon oxide compounds, particularly those potentially involved in development from rocky bodies to planetary masses [27]. Compared to argon matrix experimental data, the vibrational frequencies for the molecules SiO2, SiO3, Si2O3, and Si2O4 become less accurate as the complexity of the molecules increases but should still be predictive of infrared characteristics of silicon oxides as they form clusters in space …


Multi-Configurational Investigation Of Thermolytic Pathways Of Highly Strained Ring Systems, Jeffrey Dwayne Veals Jan 2012

Multi-Configurational Investigation Of Thermolytic Pathways Of Highly Strained Ring Systems, Jeffrey Dwayne Veals

Electronic Theses and Dissertations

The isomerization pathways of model high energy structures are of interest because of their relation to high energy density fuels. Electron resonance has been found to greatly affect the relative activation barriers for several isomerization pathways, and the major goal of this research is to accurately describe its role in determining the relative barriers for strain energy release pathways. This research is centered around the potential energy surfaces (PES's) for ? bond breaking and ? bond rotation in these highly strained structures. Of particular interest was how would resonance and or electronegativity affect the allowed/disallonature of the activation barriers in …


On The Nature Of Weak Intermolecular Forces: A First Principles Approach To Hydrogen Bonding And Pi-Type Interactions, Kari Lorene Copeland Jan 2012

On The Nature Of Weak Intermolecular Forces: A First Principles Approach To Hydrogen Bonding And Pi-Type Interactions, Kari Lorene Copeland

Electronic Theses and Dissertations

Computational quantum chemistry is a branch of chemistry that is based on quantum mechanics. In this field, chemical phenomena is represented in mathematical form and computers are used to provide numerical solutions to rigorous mathematical equations. Through this medium, the properties of atoms and molecules are calculated with high accuracy. Chapter 1 opens with a general discussion of science, the development of atomic theory and computational chemistry. Electronic structure theory is more extensively reviein Chapter 2. Hydrogen bonding and dispersion forces are defined in Chapter 3, and the procedures used to computationally study these type interactions are considered. Chapter 4 …