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Showing 1 to 20 of 58 for “"formation energy"”.
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X -Ray and Pressure Measurements on Helium Solids
… Laboratory are also presented here. The vacancy formation energy of fcc 4He at 10.4 cm3 /mol was obtained by two different methods. In addition, c/a ratios were determined to be ideal for hcp 4He and hcp 3He near 10 cm3/mol.
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Merging quadratic programming with kernel smoothing for automated cluster expansions of complex lattice Hamiltonians
… physics. Throughout the thesis we treat formation energy as the fundamental physical observable to expand on since the predominant application of cluster expansions is the extraction of robust approximations for configurational energetics in alloys and oxides. We therefore present the …
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Path Integral Monte Carlo Simulations of Helium: From Superfluid Droplets to Quantum Crystals
… results. In addition, we calculated the vortex formation energy for both pure droplets and droplets doped with linear impurities, and found that the linear impurities had a negligible impact on the formation energy. A possible spectroscopic signature of vortices in doped helium droplets was …
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Formation and dynamics of defects in pure and ion implanted a-titanium studied by quantum simulations
… been performed to study energetics of defects formation and diffusion in pure and krypton implanted hexagonal closed-packed (h.c.p) titanium. We employed the ab initio electronic structure calculations to study the formation energies of Ti vacancies and divacancies, Kr interstitials, and the …
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It's Not a SKZCAM! Accurate Surface Chemistry at Low Cost
… for fundamental quantities like the adsorption energy and oxygen vacancy formation energy to be calculated. Consistently achieving accurate predictions will require going beyond the standard density functional theory (DFT) to methods like coupled cluster theory with single, double, and …
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CO oxidation catalysis with substituted ceria nanoparticles
… of CuO/CeO₂ catalysts. The oxygen-ion vacancy formation energy is introduced as an activity descriptor to rationalize trends in the catalytic activities measured for MyCe₁-yO₂-x nanoparticles that span over three orders of magnitude. As such, the DFT-calculated vacancy formation energy serves …
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The effect of Niobium on the defect chemistry and corrosion kinetics of tetragonal ZrO₂ : a density functional theory study
… other phases of zirconia. DFT calculated defect formation energies are adjusted for finite temperature effects by accounting for thermal vibrations. Adjusted defect formation energies are then used to construct Kroger-Vink diagram for defect equilibrium concentrations at applicable p02 levels. …
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Quenching and annealing of lattice vacancies in pure lead
… rates were between 1 and 3X10 4 °C/sec. The formation energy for a lattice vacancy was determined to be 0.54+0.02 eV and the resistivity for one atomic percent vacancies was found to be 2.8+0.1 po-cm. Annealing studies indicated that the vacancy behavior of lead is similar to other …
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MAX phases as an electrocatalyst support material: a DFT study
The insatiable global demand for energy cannot be sustained by fossil fuels without irreparable damage to the environment. Various alternative energy sources are being investigated to provide renewable clean energy. One promising technology is the hydrogen fuel cell, which uses hydrogen and oxygen …
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AB initio study and design of 2D materials/III-nitrides-based post-CMOS devices using first-principles multiphysics simulation framework
… such as Ta, substituting Mo to achieve negative formation energy values with impurity states all sitting at less than 0.1 eV from the valence band maximum (VBM), making them the optimal p-type dopant candidates. Moreover, our 5x5 cell model shows that B, a group III element, can induce impurity …
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Hydrogen effects on the point defect spectrum in Fe-C alloys
… This critical-like behavior suggests an energy activation mechanism which can be characterized by an effective defect-cluster formation energy barrier. By analogy with similar activated processes such as the liquid-to-glass transition in super-cooled liquids, we postulate that this …
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Crystallographic origins of fast-ion conduction in pyrochlore
… fluorite structure. A decrease in Frenkel-defect formation-energy and an increase in the migration enthalpy accompanies the disordering. We have executed several studies of pyrochlore structures employing neutron and x-ray powder diffraction. In particular, we have focused on high-temperature …
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Assessing Structure–Property Relationships of Crystal Materials using Deep Learning
… quantum-chemical calculated properties (i.e., formation energy) for an enormous number of crystal systems. Chapter 1 briefly introduces some fundamental theory of deep learning models (i.e., CNN, GNN) and advanced analysis methods (i.e., saliency map). In Chapter 2, the convolutional neural …
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The effect of high pressure on the thermoelectric power and resistance of aluminum and gold
… and the impurityvacancy pair. Values for the formation energy and the volume are obtained for each of these defects. The effect of vacancies in gold is dominated by the effect of pressure on the lattice so that no quantitative results can be determined. An effect consistent with a monovacancy …
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Distributed autonomy and formation control of a drifting swarm of autonomous underwater vehicles
… swarm strategy for a group of AUVs, termed formation control, with consideration to the constraints of the underwater domain. Four formation control algorithms, each developed and tested within the MOOS-IvP framework, are presented. In addition, a 'formation quality' metric is introduced. …
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Deep understanding of degradation in lithium ion batteries through experimental and first-principles study
… solid electrolyte interphase (SEI) layer formation, and mechanical fracture. To address these issues, applying an ultrathin coating onto active materials via Atomic Layer Deposition (ALD) is an efficient way. Although numerious works have been done for active material performance …
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Distributed autonomy and formation control of a drifting swarm of autonomous underwater vehicles
… swarm strategy for a group of AUVs, termed formation control, with consideration to the constraints of the underwater domain. Four formation control algorithms, each developed and tested within the MOOS-IvP framework, are presented. In addition, a 'formation quality' metric is introduced. …
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Energy deposition into heavy gas plasma via pulsed inductive theta-pinch
… objective of this research is to study the formation processes of a pulsed inductive plasma using heavy gases, specifically the coupling of stored capacitive energy into plasma via formation in a theta pinch coil. To aid in this research, the Missouri Plasmoid Experiment Mk. I (and later Mk. …
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Density Functional Theory Study of Two-Dimensional Boron Nitride Films
… particular, I first studied the properties (i.e. formation energy, defect states, and structure) of point charged defects in monolayer and bilayer hexagonal boron nitride, and subsequently, I focused on the linear and nonlinear mechanical properties of boron nitride films with sp2 and sp3 bonding …
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First principles modelling of tunnel field-effect transistors based on heterojunctions of strained Germanium/InGaAs alloys
… field-effect transistor (FET) and the demand for energy-efficient appliances motivate the study of alternative devices. The device under consideration is the biaxial tensile-strained Germanium on InGaAs alloy tunnel FET (TFET). The type of device depends on the band alignments at the …
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