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 41 for “"Electronic structure theory"”.
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Advanced electronic structure theory: from molecules to crystals
In dieser Dissertation werden ab initio Theorien zur Beschreibung der Zustände von perfekten halbleitenden und nichtleitenden Kristallen, unter Berücksichtigung elektronischer Korrelationen, abgeleitet und angewandt. Als Ausgangsbasis dient hierzu die Hartree-Fock Approximation in Verbindung mit …
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Modern Electronic Structure Theory using Tensor Product States
… product states which exploits local molecular structure to significantly reduce the number of SCI variables. We demonstrate the potential of this method, called tensor product selected configuration interaction (TPSCI), using a few model Hamiltonians and molecular examples. These numerical …
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Characterizing Non-Covalent Interactions And Peptide Bond Formation With Electronic Structure Theory
… subatomic particles. The advancement of quantum theory and computer technology has driven quantum mechanical analyses toward routine in the chemist's laboratory. Chapter 1 briefly outlines some comfailures of classical mechanics from a historical standpoint. Chapter 2 provides a mathematical …
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Extending the predictive power and scope of electronic structure theory and quantum transport
… wrote his first article on Density Functional Theory, he could never have predicted its eventual impact on computational materials science. Almost 50 years after his original article, the field has seen tremendous improvement both in computer hardware and in software algorithms, and the …
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Applications Of Electronic Structure Theory To Problems In Unimolecular Dissociation And Inorganic And Biochemical Systems
… has been investigated using density functional theory and coupled cluster methods. Ab initio classical trajectory calculations have been carried out to obtain a better model of the molecular dynamics. The molecular dynamics simulations yield a branching ratio of ca 80% for the H2 elimination …
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Applications of electronic structure theory to problems in strong-field chemistry, inorganic chemistry, and nanomaterial systems
… covers research performed on applications of electronic structure theory to various fields of chemistry and is divided into eight chapters. Chapters 2 through 4 describe a series of related works which explore applications of excited state electronic structure methods to problems in strong …
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Towards Efficient and Scalable Electronic Structure Methods for the Treatment of Relativistic Effects and Molecular Response
In the context of electronic structure theory, formal theoretical development must be accompanied by efficient and scalable computer implementation in order to study molecular systems at experimentally relevant scales. Thus, this work outlines several advances in the development of efficient and …
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Development of polarizable force fields for proteins
… field for proteins based on classical mechanics, electronic structure theory and the combined quantum mechanical molecular mechanical method. In the first model, the classical force field is augmented with the explicit polarization energy term yielding a polarizable intermolecular potential …
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Theoretical Studies on the ultrafast photodissociation of molecules
… the branching ratio. A detailed investigation of electronic structure theory methods forms a large part of this research. We apply it to the FNO molecule, a system in which there is coupling amongst the states giving rise to certain topological features on the first excited state. These features …
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Theoretical investigation of solar energy conversion and water oxidation catalysis
… energy economy. In this work, I apply electronic structure theory and molecular dynamics simulation methods to understand some of the detailed mechanisms behind solar energy conversion and water oxidation catalysis. I will present a detailed atomistic picture of charge separation …
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On the Nature of Weak Intermolecular Forces: a First Principles Approach to Hydrogen Bonding and Pi-Type Interactions
… discussion of science, the development of atomic theory and computational chemistry. Electronic structure theory is more extensively reviein Chapter 2. Hydrogen bonding and dispersion forces are defined in Chapter 3, and the procedures used to computationally study these type interactions are …
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Excited states and electron transfer in solution : models based on density functional theory
… greatly from accurate, computationally tractable electronic structure methods for excited states. Here we apply two approaches based on density functional theory (DFT) to predict excitation energies and electron transfer parameters in organic chromophores and semiconductors in solution. First, we …
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Weak interactions and excited states from Coulomb-attenuated DFT
Density functional theory (DFT) is currently the most widely applied electronic structure theory in Chemistry. It is favoured for its computational efficiency, coupled with good accuracy. Although formally exact, approximations are required when practically applied. In the Kohn-Sham formalism, …
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Tddft Derivative Couplings And Other Topics In Quantum Chemistry
… which involve both the ground and excited electronic states of a molecule, can promote processes otherwise inaccessible by normal reactions. In general, photochemical reactions may be classified as adiabatic or nonadiabatic depending on whether the reaction takes place on the same adiabatic …
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Accelerating vibrational free energy calculations for anharmonic crystals
… particular on vibrational self-consistent field theory (VSCF). Firstly, the mathematical framework within which vibrational modelling takes place is detailed. The approximations which must be made are introduced, and the limitations imposed by these approximations are explored. Then the existing …
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Application of quantum Monte Carlo methods to homogeneous electron and electron-hole systems
… electron gas, and a hole-doped electron gas. Electronic structure theory is briefly reviewed before discussing in more detail the quantum Monte Carlo methods used in this thesis. A study of the three-dimensional spin-polarised homogeneous electron gas (HEG) is then reported, where the …
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Characterizing water-metal interfaces and machine learning potential energy surfaces
… we first discuss the fundamentals of ab initio electronic structure theory and density functional theory (DFT). We also discuss statistics related to computing thermodynamic averages of molecular dynamics (MD). We then use this theory to analyze and compare the structural, dynamical, and …
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Holomorphic Hartree-Fock Theory: Moving Beyond the Coulson-Fischer Point
… (HF) states has been proposed to predict electronic energies in this type of system. However, NOCI has previously been hindered by the disappearance of HF states as the molecular structure changes, creating kinks and discontinuities in the energy. This thesis develops a new theory - …
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A theoretical study of molecular crystals
… was studied with this method and the energies, structures, harmonic, and anharmonic frequencies of the infrared- and/or Raman-active vibrations, phonon dispersions, and inelastic neutron scattering (INS) were calculated. A systematic hierarchy of methods was applied from Hartree–Fock (HF) to …
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Computational investigations of the electronic structure of molecular actinide compounds
In this PhD thesis the electronic structure of a range of actinide compounds has been investigated using density functional theory. The reason for using DFT instead of other methods is mainly due to the size of the compounds which makes multireference calculations prohibitively expensive, but also …
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