Global ETD Search
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Showing 1 to 20 of 26 for “"Finite systems"”.
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Phase transitions in magnetic clusters and other finite systems
… phase transitions of magnetic clusters or other finite systems. We show that phase transitions in finite systems, which can be experimentally seen only in floppy humps of the specific heat or the magnetic susceptibility, can be quantitatively described by an analysis of an optimized estimation of …
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Path integral Monte Carlo simulations and their relation to recent advances in nanophysics
… Part three is on thermodynamic properties of finite systems and consists of three already published articles. While the first chapter of this part is about a recursion formula for the canonical occupation number, in the following chapters a new classification scheme for phase transitions in …
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Wärmeleitfähigkeit von 4 He in der Nähe des superfluiden Phasenübergangs in begrenzter Geometrie
… a 2nd order phase transition. For the infinite system very precise calculations based on renormalization group theory have been published. In most cases there is good agreement of the theoretical predictions with both experiment and computer simulation. This comparison confirms the main …
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Representing processes as Update Automata and Transducers
… functions on arbitrary domains governed by a finite automaton. We show the scope of this methodology by modeling a variety of processes, including database networks, interactive proofs, finite-state transducers, and financial ledgers. We produce a novel solution method and associated …
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Physical models of protein folding within the energy landscape theory
… from the statistical mechanics of disordered systems, polymers, and phase transitions of finite systems. The theory provides an interpretation of results from fast folding experiments as well as minimalist models used in computer simulations.
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Infinite graphs generated by tree rewriting
Finite graphs and algorithms on finite graphs are an important tool for the verification of finite-state systems. To transfer the methods for finite systems, at least partially, to infinite systems a theory of infinite graphs with finite representations is needed. In this thesis the class of the …
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Nonperturbative renormalization in classical φ4 theory
… to study nonrelativistic quartic interacting systems. The model studied is that of classical real scalar φ4 theory. A variety of techniques are used including a rescaling of a nonlinear complete basis, a limit of finite periodic systems, and an analytic calculation of RG equations using a …
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Development of large scale tight-binding methods, and application to electron transfer in symmetric dielectric barrier discharges (DBDS)
… allowing us to simulate multi-million atom systems on a large memory node on the campus cluster, as well as demonstrations of larger systems and faster, more accurate, simulations on the BlueWaters supercomputer. Next, we investigate the underlying microscopic mechanism for electron transfer …
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Microwave Properties of Helical Resonators
… as mode number is increased. The dispersion of infinitely long helical structures is characterised, demonstrating their predictive capability for lower-order modes in finite systems and their tunability through geometric tailoring. Additionally, a more complex two-handed variant of the …
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Exponential Random Graphs and a Generalization of Parking Functions
… by the Legendre-Fenchel transform.</p> <p>For finite systems, we analyze the mixing time of exponential random graph models. The mixing time of unweighted exponential random graphs was studied by Bhamidi, Bresler, and Sly. We extend upon the work of Levin, Luczak, and Peres by studying the …
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Cluster Dynamical Mean-Field Theory: Applications to High-Tc Cuprates and to Quantum Chemistry
… study problems in strongly correlated electron systems, including high-Tc cuprate superconductors as well as a few quantum chemical reference systems. We start with an introduction to the background of the interacting electron systems, followed by a brief description on the current understanding …
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Wannier Functions and Their Role in Improving Density Functional Approximations
… error in density functional approximations. In finite systems, delocalization error can be attributed to the incorrect treatment of fractional electron charge whereby the total energy deviates from the correct behavior of linear interpolation between integer points. For bulk systems the …
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Vibration from underground railways: considering piled foundations and twin tunnels
… domain. Methods for adapting models of infinite structures to simulate finite systems using mirror-imaging techniques are described. The interaction between two neighbouring piles is considered using the method of joining subsystems, and these results are extended to formulate models for …
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Dynamics of electrons and excitons in nanoclusters and molecules studied by many-body Green's function theory
… of efficient and economic photovoltaic (PV) systems harvesting solar energy is one of the grand challenges for engineering and scientific researchers. The theoretical conversion limit of a single-junction solar cell is 31% according to Shockley and Queisser (SQ), which the most advanced …
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Monte Carlo analysis of non-equilibrium steady states and relaxation kinetics in driven lattice gases
… the characteristic oscillations that occur in finite systems away from half-filling. As expected, correlations are weak in three dimensions and consequently the mean-field description is adequate. We also investigate the relaxation towards the non-equilibrium steady state in the two-time …
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Symplectic transformations and entanglement in finite quantum systems.
Quantum systems with finite Hilbert space are considered. Position and mo- mentum states and their relation through a Fourier transform, displacement in the position-momentum phase-space, and symplectic transformations are introduced and their properties are studied. Symplectic Sp(2l;Zp) trans- …
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Taming the Inverse and Forward Problems in Density Functional Theory
… In the context of inhomogenous one-dimensional finite systems, these developments permit an improved understanding of $f_\text{xc}$ in itself, and in relation to various applications, such as the optical spectrum and ground-state correlation energies using the adiabatic connection …
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Pure and Mixed Strategies in Cyclic Competition: Extinction, Coexistence, and Patterns
… [50], we employ Monte Carlo simulations to study finite systems. In chapter 3 the results of a previously published paper [49] are presented and expanded upon, where we study the extinction time of four cyclically competing species on different lattice structures using Lotka-Volterra dynamics. We …
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Poisson representation methods for stochastic models of chemical reactions
… some general features of chemical reaction systems whose steady state is thermodynamic equilibrium. The solutions for such systems are discussed from grand canonical and canonical ensemble points of view. Basic formulae for the two time correlation functions are derived using the Poisson …
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