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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 45 for “"Electronic structure methods"”.
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Automated Implementation of Advanced Electronic Structure Methods
… the development of advanced many-body electronic structure methods. However, the derivation and efficient implementation of these theories constitute a significant bottleneck. As the rank of the associated tensors increases, the governing equations explode in complexity, rendering …
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Electronic Structure Methods for the Investigation of Nonadiabatic Dynamics
… of the interface between nuclear dynamics and electronic structure is crucial for describing excited state dynamics in photoexcited systems, a key aspect of modelling the efficiency of photovoltaic devices, among other applications. There has been a proliferation of techniques for approaching …
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Using data-derived charge densities in electronic structure methods
… a collection of atoms using standard ab initio methods is typically large. This limits the scale of phenomena that can be studied in both length and time. Data-driven techniques have established a pragmatic extension to ab initio calculations, balancing reductions in the calculation time with …
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Electron-proton nonadiabaticity: characterization and development of non-Born-Oppenheimer electronic structure methods
… of the Born-Oppenheimer approximation between electronic and nuclear motions engenders the need for accurate characterization of the degree of nonadiabaticity. Furthermore, in regimes where the inclusion of these effects is vital, as it is for PCET systems, the development of …
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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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In Pursuit of Local Correlation for Reduced-Scaling Electronic Structure Methods in Molecules and Periodic Solids
Over the course of the last century, electronic structure theory (or, alternatively, computational quantum chemistry) has grown from being a fledgling field to being a "full partner with experiment" [Goddard Science 1985, 227 (4689), 917--923]. Numerous instances of theory matching experiment to …
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Breaking the curse of dimensionality in electronic structure methods: towards optimal utilization of the canonical polyadic decomposition
… the fact that higher-order tensors (HOTs) plague electronic structure methods and severely limits the modeling of interesting chemistry problems, introduction and application of higher-order tensor (HOT) decompositions, specifically the canonical polyadic (CP) decomposition, is fairly limited. The …
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Theoretical Simulations of Optical Rotation and Raman Optical Activity of Molecules in Solution
… techniques such as optical rotation (OR), electronic circular dichroism (ECD), and Raman optical activity (ROA) provide the means to probe molecular dissymmetry, which is the arrangement of atoms that is not superimposable on its mirror image. However, the application of chiroptical methods …
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Dynamics of UV -Excited Uracil, Thymine, and Cytosine
… spawning molecular dynamics and high level electronic structure methods. This work has involved both gas-phase and aqueous dynamics as well as simulation of the time-resolved photoelectron spectrum, transient absorption, fluorescence, and reaction rates. With these findings, complete …
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Coupled-Cluster Methods for Large Molecular Systems Through Massive Parallelism and Reduced-Scaling Approaches
Accurate correlated electronic structure methods involve a significant amount of computations and can be only employed to small molecular systems. For example, the coupled-cluster singles, doubles, and perturbative triples model (CCSD(T)), which is known as the ``gold standard" of quantum chemistry …
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Accurate Treatments of Electronic Correlation: Phase Transitions in an Idealized One-Dimensional Ferroelectric and Modelling Experimental Quantum Dots
… idealized dots, spherical and squashed, quasi-2D structures, are analyzed. In the first QMC is contrasted with a large set of commonly used electronic structure methods including MSFT, KLI, LSDA, and CCSD, and in the second we scrutinize whether SDW states truly exist as predicted by LSDA. In …
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Development of electronic structure and kinetics methods for the rational design of electrocatalysts
… we explore ways to improve existing modeling methods, and how to apply these methods to design novel graphite-conjugated catalysts (GCCs). For improving electronic structure methods, we first present an extended study of bootstrap embedding theory (BET) and its ability to recover static …
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Finite-Difference and Analytic-Gradient Approaches for Simulating Vibrational Circular Dichroism Using Second-Order Møller-Plesset Perturbation Theory and Configuration Interaction
… interaction with double excitations (CID) electronic structure methods. Finally, we formulate an analytic implementation of the MP2 and configuration interaction including single and double excitations (CISD) AATs.
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Theoretical Characterization of Non-Covalent Weakly Bound Clusters Through the Application of Sophisticated Computational Quantum Chemistry Methodologies and the Development of Integrated Fragmentation Techniques
… of these interactions requires sophisticated electronic structure methods employing large basis sets. This methodology becomes extremely computationally demanding as the size of the system increases. This work presents benchmark data and explores methods for obtaining highly accurate ab initio …
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Constrained Density-Functional Theory--Configuration Interaction
… thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density Functional Theory and improves upon it by including higher level treatments of …
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Quantum Nuclear Dynamics: Application to Spin-Forbidden Transitions and Lifetime of Vibrational States
… energy and dipole moment curves for the ground electronic states of these molecules and ions are computed with the coupled cluster with single, double, and triple excitations (CCSDT) and multireference configuration interaction (MRCI) electronic structure methods. The vibrational energies and …
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Dynamical effects in crystalline solid state systems: theory of temperature dependent optical response of bulk gaAs and vibrational modification of C(111) 2 x 1 Surface in Comparison to Experiment
… incorporates dynamical effects in atomistic electronic structure and related calculations. This research, fundamental by nature, brings about a deeper understanding of the dynamical processes in a range of materials. This establishes technologically important correlation with experimentally …
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Characterization Of Charge Accommodation In Biologically Important Hydrogen-Bonded Clusters
… as effects of surface-enhanced Plasresonances. Electronic structure methods were employed for accurate spectral assignment and identification of structural motifs.
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Advances in Multiconfiguration Pair Density Functional Theory and Applications to Excited State, Singlet-Triplet Gaps and Magnetism
Computational chemistry methods based on quantum mechanics play a fundamental role in explaining and predicting the properties of atoms and molecules such as excitation energies, electronic spectra, magnetism, characterization of chemical bonds, catalysis etc. It is therefore important to be able …
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Joint Density-Functional Theory For Energetics And Spectroscopy In Complex Aqueous And Nonaqueous Solvents
… to study using standard, off-the-shelf ab initio electronic structure methods. This is because a single configuration of molecular positions in the solvent (a "snapshot" of the fluid) is not necessarily representative of the thermodynamic average. To obtain any thermodynamic averages (e.g. free …
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