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 18 of 18 for “"reduced scaling"”.
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Towards a Reduced-Scaling Method for Calculating Coupled Cluster Response Properties
… and storage requirements exhibit polynomial scaling with the size of the system. For example, the coupled cluster singles and doubles method with the perturbative inclusion of triples: the CCSD(T) model, which is considered to be the ``gold standard'' of quantum chemistry scales as 𝑂(N⁷) in …
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Coupled-Cluster Methods for Large Molecular Systems Through Massive Parallelism and Reduced-Scaling Approaches
… towards two directions: parallel computing and reduced-cost/scaling approaches. Parallel computing can utilize more computational resources to handle systems that demand more substantial computational efforts. Reduced-cost/scaling approaches, which introduce approximations to the existing …
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In Pursuit of Local Correlation for Reduced-Scaling Electronic Structure Methods in Molecules and Periodic Solids
… a one-body wavefunction-based method, the scaling is formally N⁴, and post-Hartree-Fock methods fare even worse. The coupled cluster singles, doubles, and perturbative triples method [CCSD(T)], which is frequently referred to as the "gold standard" of quantum chemistry, has an N⁷ scaling, …
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Affordable Quantum Chemistry via Data-Driven and Local Approximations to Non-Covalent Interactions
… with the development and implementation of reduced-scaling dispersion algorithm. This algorithm allows for reference interactions energies to be generated at a reduced computational cost.
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Local Correlation Approaches and Coupled Cluster Linear Response Theory
… calculations must be used in conjunction with reduced-scaling methods in order to broaden the range of applications to larger systems. In this work, we introduce some of the underlying theory behind such calculations and test the performance of several local correlation techniques for …
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The Unreasonable Usefulness of Approximation by Linear Combination
… theory and then we attempt to design a linear scaling massively parallel electron correlation strategy based on second order perturbation theory.
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Development and Assessment of Pair Natural Orbitals Coupled Cluster Quadratic Response Properties
… and materials. Through the incorporation of reduced-scaling techniques, such as local pair natural orbitals (LPNOs), these advancements allow us to match experimental results and probe the fundamental behavior of complex systems. However, while significant progress has been made for …
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Towards an Improved Method for the Prediction of Linear Response Properties of Small Organic Molecules
… method. However, the high-order polynomial scaling of coupled cluster theory makes it intractable for numerous large calculations, including the conformational averaging required for optical rotation calculations in solution. We therefore attempt to reduce the scaling of a linear response …
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Exploration and Optimization of the One- and Many-particle Basis Sets in Modern Explicitly Correlated Electronic Structure
… AOs, even for neutral species. Although modern reduced-scaling formulations of explicitly correlated many-body methods have become routinely applicable to systems with hundreds of atoms, application of F12 methods to large molecular systems can be severely hampered due to the onset of poor …
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Automated Implementation of Advanced Electronic Structure Methods
… is the extension of automated implementation to reduced-scaling methods, which exploit the sparsity inherent in electronic correlation. We introduce a novel "tensor-of-tensors" data structure designed to manage the irregular sparsity patterns of Pair Natural Orbital (PNO) formulations. This …
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Explicitly Correlated Methods for Large Molecular Systems
… However, they suffer from very steep scaling behavior with respect to an increase in the size of the system as well as very slow convergence of the correlation energy with respect to the basis set size. Thus these methods are limited to small systems of up to a dozen atoms. The first …
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Selective salt recovery from reverse osmosis concentrate using inter-stage ion exchange
… and chloride. The sodium chloride stream, with reduced scaling potential, can be treated further by a second reverse osmosis stage or another volume reduction technique to recover additional fresh water. The resulting concentrated sodium chloride stream can be used as ion exchange regeneration …
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The effectiveness of antiscalants when used on multi-stage flash distillers.
… possibility of increasing water production as reduced scaling will allow a number of currently operating MSF plants to increase their top brine temperatures.
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The Efficient Computation of Field-Dependent Molecular Properties in the Frequency and Time Domains
… CC method suffers from high-degree polynomial scaling. In addition to the ground-state calculation, computing dynamic properties requires the description of sensitive excited-state effects. The cost of such methods often prohibits the accurate calculation of response prop- erties for systems of …
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Breaking the curse of dimensionality in electronic structure methods: towards optimal utilization of the canonical polyadic decomposition
… and create a route for others to develop reduced-scaling electronic structure theory methods using the CP decomposition. In Chapter 2, we introduce the robust tensor network approximation. This approximation is a way to, in general, eliminate the leading-order error associated with …
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Development of seawater electrolysis with low-cost membranes for sustainable cement production and pretreatment
… such as improved water recovery rates and reduced scaling of desalination membranes. The simultaneous recovery of freshwater and valuable resources like lithium further enhances the process’s potential for sustainable seawater resource utilization. UF Membrane electrolysis also presents a …
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Investigation of real-time coupled cluster methods for the efficient calculation of optical molecular properties in the time domain
… challenge due to their high-order polynomial scaling. For RT-CC methods, two aspects may be explored to improve the efficiency, the numerical techniques regarding the RT propagation and the reduced-scaling methods regarding CC itself. In this work, we start with the exploration of the hardware …
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EFFECT OF CRACK-REDUCING TECHNOLOGIES AND SUPPLEMENTARY CEMENTITIOUS MATERIALS ON SETTLEMENT CRACKING OF PLASTIC CONCRETE AND DURABILITY PERFORMANCE OF HARDENED CONCRETE
… durability, based on ASTM C666 Procedure B, scaling resistance, based on a modified version of Canadian Test BNQ NQ 2621-900 Annex B, and characteristics of the air-void system, obtained following ASTM C457. The research also examined the correlation between air-void characteristics, …