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 51 for “"Linear Scaling"”.
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Conjugate gradient density matrix search: A linear scaling alternative to diagonalization
… theory Hamiltonians have demonstrated near-linear scaling with molecular size for these steps. These advances leave the ${\cal O}(N\sp3)$ diagonalization bottleneck as the rate determining step for very large systems. In this work, a conjugate gradient density matrix search (CG-DMS) method …
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Development of more accurate computational methods within linear-scaling density functional theory
… Traditional implementations of DFT are cubic-scaling which limits the size of the systems that can be studied. However recently developed linear-scaling methods, such as onetep, are available which allow much larger systems to be considered. Regardless of scaling DFT has limitations as the …
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Linear scaling density functional theory with Gaussian orbitals and periodic boundary conditions
… method (FMM). The FMM achieves not only linear scaling of computational time with system size but also high accuracy, which is pivotal for avoiding numerical instabilities that have previously plagued calculations with large bases, especially those containing diffuse functions. The …
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Linear-Scaling Density Functional Theory and Theoretical Electron Energy Loss Spectroscopy Investigations of Surfaces and Defects in Nanomaterials
… theory will be discussed, with a focus on the linear scaling methods employed by onetep. A method for the prediction of spectra will be shown, with emphasis on the construction of the matrix elements needed. This method is tested against both other DFT codes and experiment. Once the ability of …
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An Efficient Platform for Large-Scale MapReduce Processing
… open-source solution, Hadoop. It demonstrates linear scaling for CPU-intensive processing and even super-linear scaling for indexing-related workloads. In addition, we designed a MMR live DVD which facilitates the automatic installation and con guration of a Linux cluster with integrated MMR …
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Accounting for Strong Electronic Correlation in Metalloproteins
… DFT+$U$ and DMFT can be readily married with linear-scaling DFT, meaning that these theories can be applied to protein systems containing thousands of atoms. In particular, this thesis presents the unification of ONETEP (a linear-scaling DFT code) and TOSCAM (a DMFT solver). It also presents a …
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Development of a force field with condensed phase consistent charges for N,N' - dialkylimidazolium room temperature ionic liquids
… with the investigation of the effects that the linear scaling of partial atomic charges on nonpolarisable force fields from a reference potential has on the structure and dynamics of the room temperature ionic liquids (RTILs) 1-butyl-3-methylimidazolium tetraflouroborate [C4MIM][BF4] and …
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Atomistic simulations of semiconductor and metallic nanoparticles
… (DFTB+ [2]), conventional DFT (CASTEP [3]) and linear-scaling DFT (ONETEP [4]). A brief introduction regarding some basic principles of quantum mechanics (QM) and of solid state physics is presented in the first chapter; followed by a general chapter about the classical molecular dynamics (MD) …
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The Unreasonable Usefulness of Approximation by Linear Combination
… 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 focus on those that can be …
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Predicting Transitions in Fischer-Tropsch Reactors
… Plane-wave DFT suffers from unfavourable cubic scaling and its extended basis makes vacuum space costly, limiting its applicability to large clusters and surface structures. The linear-scaling DFT code ONETEP is a good candidate for investigating these classes of system. While its metals …
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Large scale quantum mechanical enzymology
… expensive for systems of the requisite size. Linear-scaling density-functional theory (DFT) is an accurate method that can apply the predictive power of quantum mechanics to the system sizes required to study problems in enzymology. This dissertation presents methodological developments and …
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Design of a Scaled Flight Test Vehicle Including Linear Aeroelastic Effects
… for the design of a scaled aircraft using linear aeroelastic scaling is developed and demonstrated. Previous work has shown the viability in matching scaled structural frequencies and mode shapes in order to achieve consistent linear scaling of simple models. This methodology is adopted for …
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Quality-of-service provisioning in high speed networks : routing perspectives
… of existing s-approximation algorithms are linearly proportional to the adopted linear scaling factors. Therefore, two efficient algorithms are proposed for finding the optimal (the smallest) linear scaling factor such that the computational complexities are reduced. Finally, an efficient …
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A Unified Resource Platform for the Rapid Development of Scalable Web Applications
… 123 ms per request and has been shown capable of linear scaling with each application server capable of handling 120+ requests per minute. This important property of being able to seamlessly scale to developer's needs helps to eliminate the expensive scaling process. Initial users of the platform …
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Proton-coupled electron transfer reactions in bio-inspired catalysis
… behaviors of over one hundred quinones using linear scaling relationships, such as Hammett correlations, revealed linear correlations between 1 e– reduction potentials, pKa values, and 2 e–/2 H+ reduction potentials with an effective Hammett constant. More importantly, key deviations resulting …
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From Pine Cones to Minimal Surfaces: The Geometry and Mechanics of Morphing Bilayers
… of the bulk behaviour. However, the resulting linearly scaled Gauss for the stretching energy does not distinguish between planform geometries, and given recent findings concerning the influence of edge effects on preferred bending direction, the validity of the Uniform Curvature model has been …
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Large-scale density functional theory study of van-der-Waals heterostructures
… of different stacked layers. First, we utilise linear-scaling density functional theory (LS-DFT) to simulate intricate interfaces between the most promising layered materials, such as transition metal dichalcogenides (TMDC) or black phosphorus (BP) and hexagonal boron nitride (hBN). We show that …
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A Column-Row-Parallel ASIC architecture for 3D wearable / portable medical ultrasonic imaging
… programmable electronic addressing to achieve linear scaling for both hardware interconnection and software data acquisition. A 16x16 transceiver ASIC is fabricated and flip-chip bonded to a 16x16 capacitive micromachined ultrasonic transducer (CMUT) to demonstrate the compact, low-power …
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Discrete element computation : algorithms and architecture
… Neighbor search algorithms exist that exhibit linear scaling in the number of bodies. These algorithms rely, however, on the assumption of uniformly sized objects. Devaitions from this assuption, inherent in many common physical systems, significantly degrade performance. This thesis presents a …
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Application of quantum walks on graph structures to quantum computing
… scheme for generating cluster states. We see a linear scaling, better than many schemes, as doubling the size of the generating grid in our scheme produces a cluster state which is double the depth. Our scheme is able to create other interesting topologies of entangled states, including the unit …
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