Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 24 for “"first principles simulations"”.
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FIRST-PRINCIPLES SIMULATIONS OF SOLID STATE BATTERY MATERIALS
… Monte Carlo. The density functional theory simulations use fundamental quantum mechanics along with some approximations to produce accurate models of real materials. A smaller portion of the work uses kinetic Monte Carlo to provide qualitative information about the convergence properties of …
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First Principles Simulations of Hydrogen and Helium at High Pressures
We also study the equation of state of hydrogen, helium and hydrogen-helium mixtures at pressures beyond 200 GPa. We find very good agreement between both simulation methodologies for pressures beyond 600 GPa. From the equation of state calculations, an analysis of the miscibility properties of the …
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Thermoelectric Energy Conversion: First-principles Simulations, Energy Harvesting and Deep Cooling Systems
… to understanding thermoelectric transport via first-principles simulations and the expansion of thermoelectric technologies through developing power generators using human metabolic heat and low-temperature freezers for vaccine storage. First, we present density functional theory simulations of …
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Accurately computing excited states and lattice dependent tight-binding models from first principles simulations
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2022-04-06 without embargo terms
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First-principles simulations of the oxidation of methane and CO on platinum oxide surfaces and thin films
… oxidation of carbon compounds by means of first-principles atomistic thermodynamics calculations and molecular dynamics simulations based on density functional theory. On the Pt(111) surface the most stable superficial oxide phase is found to be a thin layer of alpha-PtO2, which appears not …
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Nonequilibrium electron dynamics under energetic ions or electrons irradiation
Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2027-08-01
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Charge Density Waves and Superconductivity in Rare Earth Compounds from First Principles
… To better understand this competition, I use first-principles simulations to study rare-earth tritellurides (RTe3) and doped rare-earth trihydrides (RH3), which host superconducting states when their charge-density-waves/structural transitions are suppressed. I develop useful computational …
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Lattice Dynamics in Temperature-driven and Photo-induced Phase Transitions
… effects of phonon anharmonicity without using first-principles calculations, for instance to obtain renormalized second- order and higher-order force-constants. Moreover, pump-probe experiments can now resolved femtosecond atomic dynamics by using an ultrafast laser pulse to excite materials …
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Computational Study of Carbon-Based Low-Dimensional Materials on Structures, Properties and Applications
… and applications has been investigated. First-principles simulations are employed to investigate the following topics. First of all in the 1D scenario, a comprehensive study on carbyne-one dimensional carbon chain-from its structure to properties has been conducted, and the extreme …
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Peculiar perovskites: Unraveling the unique optical response of hybrid organic-inorganic perovskites from first principles
… influence the measured optical response of HOPs. First principles simulations provide a window to examine how these atomic-scale interactions contribute piece-by-piece to the measurable optical properties of materials. In this PhD thesis, I apply and develop first principles optical calculations …
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Selected Topics on Molecular Electronics, Magnetism and Surface Science
… allow us to perform accurate and fast simulations of the ground state physical properties of crystalline solids and isolated systems with a relatively large number of atoms. Such simulations are known as ab initio or first principles simulations because no free parameters enter into …
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Computational modeling of defects in nanoscale device materials
… electronic devices has been a long-term goal of first-principles methods. First principles simulations are performed in this thesis, consisting of density functional theory (DFT) supplemented with many body perturbation theory (MBPT) methods, of native defects in bulk and slab models of …
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Scanning Tunneling Microscopy and Spectroscopy of Carbon Nanotubes Interfaced With Silicon Surfaces
… modifications to the SWNT. The growing body of first-principles simulations of the SWNT/Si(100) system was drawn upon in the interpretation of such local perturbations. Weakly adsorbed SWNTs initially unstable in the presence of the rastered STM tip could be stabilized by depassivating the …
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Non-classical methods for the simulation and design of quantum materials.
… Functional Theory, which apply traditional first-principles simulations of material physics. However, the simulation of quantum materials (whose properties are fundamentally shaped by quantum mechanics) poses a significant challenge due to their intricate electronic structure and unique …
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Lattice thermal conductivity of bulk and polycrystalline PbTe from computer simulations
… their range of application is usually limited: first-principles simulations do not allow for the study of intrinsic defects in large structures and the available classical potentials tend to overestimate the lattice thermal conductivity of the bulk material. Here, we present an optimised …
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Atomistic disorder effects on structural, electronic and phononic properties in Si1-xGex
… material properties and mechanisms. For example, first principles simulations show that atomic scale variations in composition field affect (a) quantum confinement in Si1-xGex/Si quantum dots and make larger quantum dots function like smaller quantum dots and (b) sensitivity of optical phonons …
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Multifidelity Methods for Design of Transition MetalComplexes
… from data-driven surrogate models together with first-principles simulations. A framework for data-driven inference of the quantum properties of TM complexes is developed, using artificial neural networks (ANNs) and graph-based molecular representations that facilitate rapid screening while …
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Multiscale Modeling Of The Hierarchical Structure Of Cellulose Nanocrystals
… tools capable of connecting atomistic based simulations to experiments through continuum based modeling techniques.</p> <p>First-principle density functional theory and molecular dynamic simulations were utilized at the atomistic level. Longstanding issues regarding the elastic and thermal …
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Large Scale Simulations of Conduction in Carbon Nanotube Networks
… that affect conduction in these networks. First, the factors that affect tunnelling rates between axially-aligned CNTs are investigated. Using scattering theory and tight-binding calculations, a novel mechanism is identified whereby momentum scattering induced by weak perturbations can …
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Observation and manipulation of the wave nature of phonon thermal transport through superlattices
… in nanostructures. In this thesis, we report the first experimental observations of the regimes of coherent phonon transport and phonon localization in thermal conduction through nanostructures. First, in order to better understand thermal transport through SLs, we present measurements of …
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