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Articles 1 - 9 of 9
Full-Text Articles in Computational Chemistry
Additional Information For Fully Anharmonic Ir Spectra Of Neutral Polycyclic Aromatic Hydrocarbons With Up To 38 Carbons, Nolan J. H. White, Vincent J. Esposito, Christiaan Boersma, Louis J. Allamandola, Jesse D. Bregman, Alexandros Maragkoudakis, Pasquale Temi, Ryan C. Fortenberry
Additional Information For Fully Anharmonic Ir Spectra Of Neutral Polycyclic Aromatic Hydrocarbons With Up To 38 Carbons, Nolan J. H. White, Vincent J. Esposito, Christiaan Boersma, Louis J. Allamandola, Jesse D. Bregman, Alexandros Maragkoudakis, Pasquale Temi, Ryan C. Fortenberry
Faculty and Student Publications
Interstellar aromatic infrared band (AIB) spectra are showing strong agreement with presently-computed, anharmonic spectra for various types of polycyclic aromatic hydrocarbons (PAH) determined using a novel semi-empirical quantum chemical method. Since the AIB spectrum is a blend of emission spectra from a vast number of different PAHs, likely with an array of different molecular structures, the spectra for a sample set of 31 PAHs ranging in size from naphthalene (C$_{10}$H$_8$) up to circumbiphenyl (C$_{38}$H$_{16}$) are combined giving consideration to almost all PAH structural motifs. The computed, numerical quartic force fields coupled to second-order vibrational perturbation theory clearly confirm that PAH …
Theoretical Spectroscopic Predictions Of Electronically Excited States, Noah R. Garrett
Theoretical Spectroscopic Predictions Of Electronically Excited States, Noah R. Garrett
Honors Theses
The quest for faster computation of anharmonic vibrational frequencies of both ground and excited electronic states has led to combining coupled cluster theory harmonic force constants with density functional theory (DFT) cubic and quartic force constants for defining a quartic force field (QFF) utilized in conjunction with vibrational perturbation theory at second order (VPT2). This work shows that explicitly correlated coupled cluster theory at the singles, doubles, and perturbative triples level [CCSD(T)-F12] provides accurate anharmonic vibrational frequencies and rotational constants when conjoined with any of B3LYP, CAM-B3LYP, BHandHLYP, PBE0, and ωB97XD for roughly one-quarter of the computational time of the …
Methods For Computing Rovibrational Spectral Data With Applications To Inorganic Oxides And Hydrocarbons, Alexandria Watrous
Methods For Computing Rovibrational Spectral Data With Applications To Inorganic Oxides And Hydrocarbons, Alexandria Watrous
Honors Theses
Computational chemistry focuses on finding solutions to the time-independent Schrödinger equation for systems of interest to study their molecular properties such as rovibrational spectral data. Any molecule containing more than one electron cannot be solved explicitly but coupled cluster theory offers one of the best approximations. One such application of this method is to molecules of astrochemical interest to support observation and experimental data. Chapters 2, 3, and 4 look at the performance of new couple cluster theory methods including composite and hybrid methods for ground and excited state rovibrational data. Chapters 5 - 9 use the previously mentioned methods …
Microhydration Of Hexachlorophosphate Anion, Anna Robertson
Microhydration Of Hexachlorophosphate Anion, Anna Robertson
Honors Theses
The microhydration of the hexafluorophosphate anion has been the focus of many previous experimental and computational studies, due to its use in room temperature ionic liquids.This preliminary study examines the analogous hexachlorophosphate anion and its interactions with one to two water molecules (PCl6−(H2O)n, n = 1-2), identifying the structural and energetic differences in the microhydration of PCl6− versus PF6−. A systematic investigation of the possible orientations of one to two water molecules around PCl6− was done. Full geometry optimizations were performed using the ab initio method …
A Study Of Cannabigerolic Acid And Its Derivatives Via Raman Spectroscopy And Density Functional Theory, Trevor Wolfe
A Study Of Cannabigerolic Acid And Its Derivatives Via Raman Spectroscopy And Density Functional Theory, Trevor Wolfe
Honors Theses
The cannabinoids are a class of molecules endogenous to the cannabis plant. Their scientific relevance has increased in recent years due to the mercurial legal status of marijuana across the United States. Some of the most known are cannabidiol (CBD), δ9-tetrahydrocannabinol (δ9-THC), and δ8-THC due in large part to their widespread use, especially in states where marijuana and related products are legal. However, cannabigerolic acid (CBGA) is arguably the most important cannabinoid; it is enzymatically converted into other acidic cannabinoids, which subsequently undergo non-enzymatic processes (isomerization, thermal decarboxylation, oxidation, etc.) to synthesize further cannabinoids. Although there is a wealth of …
Ab Initio Study Of The Rotation Of The C≡C Group In Benzvalyne, Advait Praveen
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
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 …
Computational And Spectroscopic Studies Of New Sulfur-Containing Dipole-Bound Anions, Nicholas Allen Kruse
Computational And Spectroscopic Studies Of New Sulfur-Containing Dipole-Bound Anions, Nicholas Allen Kruse
Honors Theses
Sulfur and Nitrogen are essential ingredients in both life-supporting and light-harvesting molecules. Their presence also usually leads to the delocalization of electrons and large dipole and quadrupole moments. Such molecules are sometimes able to form negative ions through the electrostatic binding of an excess electron. These so-called multipole-bound (dipole-bound, quadrupole-bound, etc.) anions have been shown to be important in radiation damage in biology and electron transport processes. Here, we present our recent computational and experimental results studying the creation of new multipole-bound anions.
Relative Energy Comparison For Various Water Clusters Using Mp2, Df-Mp2, And Ccsd(T):Mp2 Methods, Qihang Wang
Relative Energy Comparison For Various Water Clusters Using Mp2, Df-Mp2, And Ccsd(T):Mp2 Methods, Qihang Wang
Honors Theses
The study of water clusters is an important area of research in many disciplines, such as biology, physical chemistry, and environmental studies. However, due to the difficulty in studying larger water clusters, such as clathrate hydrates, it is beneficial to obtain accurate descriptions of smaller water clusters to use as models for larger systems via computational methods. By starting with small water clusters, such as (H2O)6, and moving into larger systems it is possible to build up data on various water structures that can determine the energetics of the various geometries within a certain number of water molecules. …