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 24 for “"Extended Systems"”.
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Optical Response Of Finite And Extended Systems
… calculation of the optical response of infinite systems within time dependent density functional theory. The use of a linear combination of local orbitals and the explicit evolution of the system in time are the main characteristics of our method. It was implemented within SIESTA and is designed …
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Model-based control of spatially extended systems
We extend a new method of control, model-based control, to the realm of partial differential equations. The hallmark of model-based control is that a particular goal dynamics is achieved by using a model for the observed dynamics to create the appropriate driving needed to make the goal dynamics an …
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Model-based control of spatially extended systems
… and use computer simulations to explore systems beyond analytic tractability such as the Burgers and the N avier-Stokes equations. With the Burgers equation a systematic investigation into the control behavior was conducted with particular attention to sensitivity of the control to model …
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Renormalization group methods for dynamics of spatially extended systems
… concept in the study of dynamics of spatially extended systems: different microscopic dynamics may be related, via coarse graining, to the same macroscopic dynamics. This thesis makes two contributions in this direction: first, we obtain the correct description of the dynamics of a continuous …
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Vibrational many-body methods for molecules and extended systems
"Vibrational many-body methods for molecules and extended systems have been developed that can account for the effects of anharmonicity in the potential energy surfaces (PESs) on energies and other observable properties. For molecules, we present a general scheme to calculate anharmonic vibrational …
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Some problems in the dynamics of spatially extended systems
… some representative problems in the dynamics of systems which have a non-trivial spatial dependence. In the first chapter, we study the perturbed sine-Gordon equation and the ""Painleve test of integrability."" We present results of our numerical studies of the d.c. driven, damped sine-Gordon …
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Anharmonic vibrational many-body theory for molecules and extended systems
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms
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Path integral calculations of coupled spin and dendrimeric systems
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-04-12 without embargo terms
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Dynamical systems approach to one-dimensional spatiotemporal chaos -- A cyclist's view
We propose a dynamical systems approach to the study of weak turbulence(spatiotemporal chaos) based on the periodic orbit theory, emphasizing the role of recurrent patterns and coherent structures. After a brief review of the periodic orbit theory and its application to low-dimensional dynamics, we …
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Stochastic dynamics in spatially extended physical and biological systems
… problems of stochastic nature in spatially extended systems: (1) a noise induced mechanism for the emergence of biological homochirality in early life self-replicators, (2) the amplification effect of nonnormality on stochastic Turing patterns in reaction diffusion systems, and (3) the …
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Model-based monitoring and diagnosis of systems with software-extended behavior
… of devices has largely operated on hardware systems. However, in most complex systems today, such as aerospace vehicles, automobiles and medical devices, hardware is augmented with software functions that influence the system's behavior. As these sophisticated systems are required to perform …
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Quantum Monte Carlo: Applications of the Twist -Averaged Boundary Conditions and the Calculation of Forces
… studying the properties of physical and chemical systems. The application of QMC to extended systems subjects to finite size effects because the simulation is often done with a small system in a super cell geometry. Periodic boundary condition is commonly used in such a setup which leads to large …
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Ratchet dynamics in nonlinear Klein-Gordon systems
… energy transport in homogeneous nonlinear extended systems in the presence of a biharmonic force and dissipation. We have shown that the mechanism responsible for unidirectional motion of topological excitations is the coupling of their internal and translation degrees of freedom. Our …
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Wavefunction-based method for excited-state electron correlations in periodic systems - application to polymers
… for determining correlated wavefunctions of extended systems in the ground state as well as in excited states is presented. It allows to fully exploit the power of quantum-chemical programs designed for correlation calculations of finite molecules. Using localized Hartree-Fock (HF) orbitals …
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Quantum Monte Carlo: Applications of the Twist-averaged Boundary Conditions and the Calculation of Forces
… studying the properties of physical and chemical systems. The application of QMC to extended systems subjects to finite size effects because the simulation is often done with a small system in a super cell geometry. Periodic boundary condition is commonly used in such a setup which leads to large …
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Backflow and pairing wave function for quantum Monte Carlo methods
… be used to compute the properties of electronic systems accurately from first principles. This thesis is mainly concerned with the development of trial wave functions for QMC. An extension of the backflow transformation to inhomogeneous electronic systems is presented and applied to atoms, …
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Spatio-temporal dynamics before population collapse
… approach of catastrophic thresholds in natural systems may result in an increasingly slow recovery from small perturbations, a phenomenon called critical slowing down. In this thesis, we used replicate laboratory populations of the budding yeast Saccharomyces cerevisiae for direct observation of …
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Diagrammatic theories for the vibrational many-body problem
… developed for and applied to small molecules and extended systems in a bound potential energy surface (PES). Diagrammatically size-consistent and basis-set-free vibrational coupled-cluster (XVCC) theory for both zero-point energies and transition frequencies, the latter through the …
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A study of the effects of spatially localized time-delayed feedback schemes on spatio-temporal patterns
… to control spatio-temporal chaos, spatially extended systems were subjected to protocols that perturbed them as a whole, often overlooking the potential stabilizing interaction between adjacent regions. We have shown that through the application of a time-delayed feedback scheme to a specific …
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Structural and electronic properties of transition metal nanoalloys and magnetic compounds
… dopant is established that can be generalized to extended systems and suggests a route to stabilize the magnetic moment of bulk Mn-Si compounds.
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