Computational Chemistry Commons^™

Applications For The Quasi-Atomic Orbital And Constrained Density Functional Theory Methods On Catalytic Reactions, Alvaro David Loaiza Orduz

LSU Doctoral Dissertations

Selective activation of C–O, C–H, and C–C bonds underpins biomass upgrading, alkane functionalization, and CO₂ conversion. Despite their importance, the electronic factors governing catalytic performance remain incompletely understood, and many industrial processes still rely on empirical trends or material-specific observations. This dissertation addresses this gap by applying density functional theory (DFT), thermodynamic decomposition, and electronic-structure analysis to identify unifying principles of reactivity across transition-metal phosphides, vanadate oxides, copper-based electrocatalysts, and mixed IrO₂–RuO₂ layers. This work examines how charge transfer, orbital localization, and ligand-induced perturbations control reaction pathways in diverse catalytic systems. C–O bond scission in 2-methyltetrahydrofuran (MTHF) and methanol was …

Designing A Data Collection And Visualization Toolkit For Scalable Tensor Algebra In Quantum Chemistry Applications, Epiya J. Ebiapia

LSU Master's Theses

Large-scale quantum chemistry computations, such as those executed with the Tensor Algebra for Many-body Methods (TAMM) framework, require careful configuration of runtime parameters to achieve high performance and cost efficiency in high-performance computing (HPC) and cloud environments. Without effective performance analysis tools, researchers risk inefficient use of computational resources, leading to longer runtimes and higher costs.

To address this challenge, this thesis presents the design and implementation of a performance profiling and visualization toolkit for TAMM, developed as part of the DOE TEC4 project in collaboration with Pacific Northwest National Laboratory, Microsoft, and Louisiana State University. The toolkit collects detailed …

Synthesis And Characterization Of Bimetallic Plasmonic Nanoparticles Using Linear And Nonlinear Spectroscopy, Daniel Babayode

LSU Doctoral Dissertations

Recent exploration in the field of nanomaterials has led to the investigation of noble metal nanoparticles for various nanomedical applications. The spectroscopy of these nanoparticles is studied using both linear and nonlinear optical processes such as second harmonic generation (SHG), two-photon fluorescence (TPF), and extinction spectroscopy. Details pertaining to the growth dynamics of silver-gold core-shell (Ag@Au CS) nanoparticles (NPs) and gold-silver-gold core-shell-shell (Au@Ag@Au CSS) nanoparticles (NPs) are currently being investigated in order to obtain better control and optimization of the nanoparticle size and surface morphology. Transmission electron microscopy (TEM) images show that the nanoparticles have tunable core and shell sizes …

A Coarse-Grained Molecular Dynamics Study Of Gas Hydrate Formation And Dissociation, Meisam Adibifard

LSU Doctoral Dissertations

The study of gas hydrates has increased significantly over the last two decades because of their potential application in energy storage, production and transportation, water desalination, refrigeration, gas separation, etc. There is a significant interest in commercially developing natural gas hydrates because the energy content of methane hydrate reservoirs (MHRs) is at least twice that of all conventional fossil fuels combined. Additionally, due to the higher storage capacity of hydrates, it is proposed to sequester CO₂ in the form of CO₂ hydrate, thereby reducing the amount of greenhouse gases. Hence, hydrates offer a dual solution to two of …

Attochemistry Regulation Of Charge Migration, Aderonke Folorunso

LSU Doctoral Dissertations

Charge migration (CM) is a coherent attosecond process that involves the movement of localized holes across a molecule. This phenomenon is potentially useful to understand the fundamental principles of photochemistry, such as light harvesting. The first part of this dissertation discusses the molecular modes of attosecond charge migration. In this work, we used first-principles calculations to investigate the modes of charge migration (CM) in halogenated hydrocarbon chains at attosecond timescales. We have simulated the creation of a localized hole on the halogen atom using constrained density functional theory (DFT) and then tracked its subsequent dynamics with time-dependent DFT (TDDFT). Our …

Computational Investigations Of Polymer Electrolytes In Aqueous Solutions, Hishara Keshani Gallage Dona

LSU Doctoral Dissertations

Polymer electrolyte membranes, an intriguing category of soft materials, are characterized by polymer backbones tethered with negatively or positively charged functional groups, finding applications from biological macromolecules to electrochemical separations in fuel cells. This dissertation focuses on computational investigations of polymer electrolytes in aqueous solutions using polypeptoids and ion exchange membranes. Polypeptoids, highly tailorable peptidomimetic polymers lacking backbone hydrogen bonding or chirality, were used as model systems. Micelles formed from these polypeptoid polymers exhibited electrostatic repulsion, which competes with charge-sodium interactions, adding complexity to predicting micelle shapes. This research refined the design strategy, enhancing micelle shape and structure through precise …

Deciphering The Role Of Molecular Interactions On The Interfacial Structure Of Aqueous And Non-Aqueous Interfaces, Dodangodage Ishara Indunil Senadheera, D I. Senadheera

LSU Doctoral Dissertations

The study focused on "Deciphering the role of molecular interactions on the interfacial structure of aqueous and non-aqueous interfaces" holds immense significance in diverse scientific and industrial domains. Our primary objective is to unravel the intricate web of molecular interactions occurring at the boundaries between aqueous and non-aqueous phases. The research presented here spans a wide scope, encompassing applications in microelectromechanical systems in the semiconductor industry, energy-efficient membranes for electrochemical separations, and renewable energy storage systems. Molecular dynamics simulations were conducted in collaboration with experimental studies, specifically atomic force microscopy, to achieve insights at the molecular level.The first project centered …

First-Principles Simulations Of Attosecond Transient X-Ray Absorption, Min Chen

LSU Doctoral Dissertations

The first part of this dissertation presents calculations of the extinction spec- tra of gold-silver/silver-gold core-shell nanospheres. The goal of this projectsis to get a deeper understanding of surface plasmonic resonance in metal nanospheres with core-shell geometry. Here, we used the finite-difference time-domain (FDTD) method and total-field/scattered-field (TFSF) framework to compute the extinction spectra of nanoparticles to determine the geometry of gold-silver/silver-gold core-shell nanoparticles. This supported experimental work on monitoring the growth dynamics of colloidal gold- silver/silver-gold core-shell nanoparticles using in situ second harmonic generation (SHG) and extinction spectroscopy.

The second and main project involved simulating attosecond transient spectra for …

Simulations Of Intruder-Free X-Ray Transient Absorption And Time-Resolved X-Ray Scattering For Probing Attosecond Electron Dynamics, Mengqi Yang

LSU Doctoral Dissertations

The motion of electrons plays a fundamental role in both physics and chemistry, and capturing such dynamics requires the ability to resolve changes at the attosecond timescale, which is enabled by the advent of ultrashort laser pulses. This dissertation aims to facilitate the interpretation of ultrafast electron dynamics and attosecond spectroscopy by real-time time-dependent density functional theory (RT-TDDFT) simulations. The first part of this dissertation focuses on improving the simulation of X-ray transient absorption spectra (XTAS) with Gaussian basis sets in RT-TDDFT by applying a filter to the transition dipole matrix. Due to the spatial limitation of atom-centered Gaussian functions, …