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Showing 1 to 20 of 79 for “"Electronic Structure Calculations"”.
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Advancing many-body methods for electronic structure calculations
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2025-02-04 without embargo terms
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Wavelets and wavelet optimized-finite differences for electronic structure calculations
To perform electronic structure calculations on inhomogenous systems, it is desirable to use methods which adapt to the problem by using a spatially-varying level of resolution. A wavelet basis can efficiently represent a function which is rapidly varying in certain regions of space. …
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A Dynamic Self-Adaptive Wavelet-Based Method for Multiscale Electronic Structure Calculations
Results are presented for the model calculations of hydrogen and helium atoms using a general three-dimensional bare Coulomb potential, as well as a three-dimensional quantum dot.
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Enabling Electronic Structure Calculations of High Z Element Containing Materials Using Dirac Relativistic DFT Methods
… it with high Z elements to alter its underlying electronic states. Presently, no method exists that can accurately capture both large system sizes and the intricate fundamental physics of the induced multiplet states in the electronic structure. As part of a collaborative effort to merge a …
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A combined approach of electronic structure calculations and spectroscopy for elucidating reaction mechanisms in organic and bioinorganic systems
… techniques are used to investigate the structure and mechanism of a variety of important chemical systems, some of which are relevant to biological energy transduction and energy harvesting. The mechanisms by which [FeFe] and [NiFe] hydrogenase enzymes catalyse the reversible reduction …
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Machine learning for electronic structure
… quantum chemistry as a means to bypass expensive electronic structure calculations, which are used to calculate quantum mechanical properties for systems of atoms. This has led to advances in a broad range of applications, largely due to the fact that ML approximations have a much lower …
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Computational Alchemy: The Rational Design of New Superhard Materials
First--principles electronic structure calculations have been performed to help identify and direct the synthesis of new superhard compounds. An improved figure of merit for hardness is identified and used to show that carbon nitrides are not likely to be harder than diamond.
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Efficient Automated Generation of Local Descriptors for Use in ab initio Electronic Structure Simulations
First-principles electronic structure calculations based on density functional theory (DFT) are well-known to have a high computational cost that scales algorithmically as O(N³), where N is the number of electrons. Reducing that cost is a key goal of the computational materials physics community …
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Formation and dynamics of defects in pure and ion implanted a-titanium studied by quantum simulations
Density-functional theory calculations have 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 …
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The Unreasonable Usefulness of Approximation by Linear Combination
… to reduce the computational cost of accurate electronic structure calculations to linear. Meaning, that the total time to solution for the calculation grows at the same rate as the number of particles that are correlated. Multiple techniques for exploiting data-sparsity are discussed, with a …
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Atomistic Modeling Predictions Of Crack Tip Behavior In Silicon Carbide
… with empirical potentials, analytic models and electronic structure calculations to illuminate key crack tip mechanisms at low temperature, high temperature and under the influence of impurities. First, I use a multifaceted modeling approach, including electronic structure calculations, MD …
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Memory and fluctuations in chemical dynamics
… Part III develops a machine learning and electronic structure framework for the computationally efficient parametrization of Frenkel Hamiltonians from snapshots of molecular dynamics simulations of organic semiconductors. Direct electronic structure calculations on these snapshots encode …
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Machine learning transferable physics-based force fields using graph convolutional neural networks
… of crystalline materials, the PES is needed for electronic structure calculations, critical for modeling semiconductors, optical, and energy-storage materials. While first principles techniques can be used to obtain the PES to high accuracy, their computational complexity limits applications to …
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First-principles approaches for accurate predictions of nanostructured materials
Nanostructured materials have attracted increasing interest in recent years due to their unusual mechanical, electrical, electronic and optical properties. First-principles electronic structure calculations (e.g., with density functional theory or DFT) provide unique insights into the …
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Ether Chemistry On Si(100) And Desorption Kinetics Of Corresponding Alkyls And Alkoxides
… desorption experiments inconjunction with electronic structure calculations, it was determined that the hydrideelimination mechanism exhibits nonadiabatic behavior. The mechanism most consistentwith the experimental kinetics involves a spin-crossing due to the electronic excitation ofthe …
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Astrochemical dynamics: Fundamental studies relevant to titan's atmosphere
… is shown, via laboratory studies combined with electronic structure calculations that the photodissociation of the dimer readily initiates atomic hydrogen (H) loss and atomic H transfer reactions forming two prototypes of resonantly stabilized free radicals, C8H3 and C4H3, respectively. In …
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Reduced basis method for quantum models of crystalline solids
Electronic structure problems in solids usually involve repetitive determination of quantities of interest, evaluation of which requires the solution of an underlying partial differential equation. We present in this thesis the application of the reduced basis method in accurate and rapid …
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Multiscale ab initio approaches to materials physics
… with ab initio methods, thus enabling ab initio calculations of free energy changes. We use this method to perform an ab initio calculation of the free energy of reconstruction in the 300 reconstruction of silicon. In the next chapters we introduce a completely new approach to electronic …
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Exciton behaviour at organic solar cell interfaces
… the influence that electric fields and chemical structure have on exciton dissociation and recombination at the interface of donor-acceptor materials. In particular, we use mixed quantum/classical dynamical simulations and electronic structure calculations to investigate several …
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Modeling and simulations of low dimensional and nanostructured materials systems at the nanoscale
… an increasing interest has been devoted to nanostructured materials, in which the basic components are nanoscopic, and low-dimensional nanomaterials such as nanoparticles, nanowires and layered materials, in which one or more dimensions are confined. This thesis deals with nanostructured …
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