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 28 for “"classical dynamics"”.
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Quantum and classical dynamics of molecular scale structures
In this thesis, I investigate the electronic properties of molecular junctions formed from single molecules. Most of my work uses the saturated alkane chain as my reference molecule to study some problems of charge transfer in nanoscale devices. Chapters 2 and 3 present a brief introduction to …
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Random matrices, quantum chaos and irreversible classical dynamics
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1996.
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Two Dimensional Autonomous Oscillatory System Solution Without Approximations by Analogy to Classical Dynamics
Made available in DSpace on 2014-12-04T21:03:13Z (GMT). No. of bitstreams: 1 6001663.pdf: 2537683 bytes, checksum: e9a81ff8eb11bc145ca8fc938436b235 (MD5) Previous issue date: 1960
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Nonlinear dynamics of a particle in an electric and magnetic field
… off", closed analytic solutions for the classical dynamics exist. However, when both fields are present, only approximate analytic solutions are available. For a weak, applied magnetic field perturbation theory may be used to construct the approximate solutions, but these solutions break …
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Matsubara Dynamics and its Practical Implementation
… quantum time-correlation functions, Matsubara dynamics, that rigorously describes how to combine quantum statistics with classical dynamics. Matsubara dynamics is based on Feynman's path integral formulation of quantum mechanics and is expected to describe the physics of any system that …
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Eigenfunctions in chaotic quantum systems
… systems strongly depends on the underlying classical dynamics. In this text a selection of articles on eigenfunctions in systems with fully chaotic dynamics and systems with a mixed phase space is summarized. Of particular interest are statistical properties like amplitude distribution and …
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Quasicentroid Molecular Dynamics
… quantum time-correlation functions using the classical dynamics of coordinates subject to thermally averaged Feynman path fluctuations (“the mean field”). This theory approximates the dynamics of systems at thermal equilibrium that follow quantum Boltzmann statistics and undergo rapid quantum …
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Spectral Properties of Magnetic Edge States
… precise quantum spectra even in the extreme semiclassical regime. The insight gained into the structure of the spectral determinant enables us to derive the semiclassical trace formula for magnetic billiards from first principles. We propose a spectral measure, which quantifies the intuitive …
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Kintamosios struktūros reguliatorių taikymo elektromechaninėse vykdymo sistemose tyrimas /
Classical dynamics optimization methods of the electromechanical servo drives are the quantitative and symmetrical optimums. These methods have advantages and disadvantages and are based on the fixed structure velocity controllers – proportional (P) and proportional-integrating (PI). In order to …
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Forward-Backward Methods for Mixed System Dynamics
… and computational efficiency in the study of its dynamics by applying mixed methods---methods that treat the two subsystems differently. In particular, the observable system is treated by a method that fully preserves its quantum character, while the treatment of its environment, the bath, …
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Investigating the foundations of quantum physics with optomechanical setups
… world ends, allowing for the emergence of classical phenomena. The extension of quantum properties to macroscopic system gives rise to paradoxes, as the well-known Schrödinger’s cat example. Among the alternatives to quantum mechanics, collapse models propose an objective modification of …
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Approximations to Matsubara Dynamics for Vibrational Spectra
… spectra, with a particular focus on anharmonic dynamics and non-fundamental transitions. All the methods investigated are approximations to Matsubara dynamics, which is a rigorous theoretical framework that recovers quantum Boltzmann-conserving classical dynamics in an extended space of smooth …
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Multi-level models of language comprehension in the mind and brain
… a lexicon. This modeling work recapitulates classical dynamics of language learning exhibited by children acquiring their first language, and more broadly presents an expanded view of the computational role of these representational systems. The second part of the thesis addresses the neural …
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A THEORETICAL INVESTIGATION OF PROSPECTS FOR MODE SELECTIVE OVERTONE PHOTOCHEMISTRY (QUANTUM DYNAMICS)
… related studies which probe the energy flow dynamics of overtone initiated photochemistry using theoretical methods. The nature of the classical dynamics for two model isomerization systems has been investigated with an assumed initially localized excitation to a high overtone vibration state …
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Intensity Modulated Proton Therapy Optimization Under Uncertainty: Field Misalignment and Internal Organ Motion
… to formulate the FMO problem into a molecular dynamics model. So that, the FMO problem can be optimized according classical dynamics system. This method combines the advantages of gradient-based algorithms and heuristic search algorithms. Next, we develop and validate a robust optimization …
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Microscopic Theory of Linear Response in Amorphous Materials
… to the generalised Langevin equation (GLE) in classical dynamics. In the first place, I extend the GLE and the corresponding FDT for more general cases where both the tagged particle and bath oscillators respond to an external oscillatory field. This is the example of a charged or polarisable …
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Dissipative Matsubara Dynamics
The two most widely used path-integral chemical dynamics methods are Ring-polymer molecular dynamics (RPMD) and Centroid molecular dynamics (CMD). Both of these were originally proposed as heuristic approximations, which were justified by analytic limits and empirical evidence.In 2015, the …
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Exploring Molecular Systems From Chemical Physics To Biochemistry Using Classical And Quantum Mechanics
… into the role of ultra-fast hydrogen dynamics in determining fragmentation products of C3H4 following exposure to intense laser fields. Classical dynamics simulations were performed starting from C3H4 isomers with 190 - 240 kcal/mol excess energy distributed randomly as nuclear …
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Quantum-classical and semiclassical path integral methods for condensed phase dynamics
Chemical dynamics are essentially quantum mechanical processes. A great variety of chemical processes such as electron transfer and energy relaxation occur in condensed phase, reactants and products embedding in a non-reactive solution/environment. Therefore, quantum dynamics in condensed phase is …
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