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 32 for “"mean-field approximation"”.
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Cluster Dynamical Mean-Field Theory: Applications to High-Tc Cuprates and to Quantum Chemistry
… thesis we use the recently developed dynamical mean-field approximation to 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 …
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Fermionic superfluids : from cold atoms to high density QCD : gapless (breached pair) superfluidity and kaon condensation
… aspects of fermionic superfluidity through a mean-field approximation. Our framework is extremely general, includes both pairing and Hartree-Fock contributions, and is derived rigorously from a variational principle. This framework allows us to analyze a wide range of fermionic systems. In …
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Many-Body Effects on the X-Ray Spectra of Metals
… spectra of metals are evaluated in a change-of-mean-field approximation using a one-dimensional nearest-neighbor tight-binding model of a metal.
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Several Reinforcement Learning Methods in Mean-Field Games with Binary Action Spaces
… have witnessed significant progress in the sub-field of machine learning known as reinforcement learning, in which interactions between intelligent agents and the environment enable agents to learn and solve sequential decision-making problems through accumulating rewards with delays. Despite …
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Correlations in the one-dimensional Hubbard model
… The calculations are well beyond one-particle mean field approximation. All correlations involving two neighboring sites are included exactly and higher order correlations are approximated. The effects of varying temperature, band filling, Coulomb repulsion and external magnetic field are …
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The possibility of ferromagnetism in the liquid state
… Kato is used. The calculations are trade in the mean field approximation. Some terms in the Hamiltonian of the system which were neglected by Honda and Kato are shown to be important when the minimization of the free energy is taken into account. It is found that, on the basis of this model, it …
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Non-equilibrium dynamics of dipole-coupled internal states in cold gases
… closed system with both static and resonant near-field dipole interactions under an external drive. By studying the uniform mean-field dynamics of the system, we find the dynamics are given by Rabi oscillations, with a bifurcation in the dynamics as a function of drive strength between small scale …
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Statistical mechanics of strongly driven Ising systems
… to a strong, randomly switching external driving field. A formalism based on the master equation to handle such nonequilibrium systems is introduced and applied to a mean field approximation, and one- and two-dimensional variants of the model. A novel type of phase transition related to …
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Examining the Dynamics of Biologically Inspired Systems Far From Equilibrium
… phenomena, that we analyze through computational means to showcase both the range of dynamics encompassed by these systems, as well as various techniques used to analyze them. The first system we model is a surface plasmon resonance (SPR) cell, a device used to determine the binding rates between …
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Ferromagnetism and transport in diluted magnetic semiconductors
… perturbative techniques are used: the Dynamical Mean Field Approximation (DMFA) and the Dynamical Cluster Approximation (DCA). The model used for Dilute Magnetic Semiconductors (DMS) incorporates the strong spin-orbit couplings of the carrier holes as found in most III-V semiconductors doped with …
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A study on the effect of lateral interactions on methanation over Fe(100)
… investigated in this thesis and in both cases, mean field approximations and quasi chemical approximation (QCA) were used and compared to incorporate lateral interactions into the kinetics. The mean field approximation over estimates the lateral interactions and considers global coverage while …
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Advanced Statistical Inference for Stochastic Quasi-Reaction Systems
… of their dynamics. The traditional local linear approximation methods for the estimation of the reaction rates face significant challenges in certain conditions. When the system is observed at short intervals, high correlations between successive observations result in numerical instability, …
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Establishing framework of quantum Monte Carlo calculation on II-V semiconductor
… While it reduces calculation cost radically, mean-field approximation of DFT can yield inaccurate description of electronic properties especially for complex, wide band gap materials. Therefore, we introduces quantum Monte Carlo (QMC) method, which is an exciting technique with benchmark …
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Ultracold Molecules: The Effect of Electromagnetic Fields
… of ultracold molecules. Electromagnetic fields can be used to create, trap, and modify the collisional dynamics of ultracold molecules, and thus the properties of ultracold molecules in electromagnetic fields is of growing importance. This thesis examines some of the effects of externally …
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Approximations to Matsubara Dynamics for Vibrational Spectra
… 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 imaginary-time Feynman paths by removing real-time quantum coherence. …
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Dynamics and Electrostatics of Membrane Proteins using Polarizable Molecular Dynamics Simulations
… However, traditionally used nonpolarizable force fields (FF) are thought to model the unique dielectric gradient posed by the lipid environment with a limited accuracy due to the mean field approximation of charge. Advancements in polarizable FFs and computing efficiency has enabled the explicit …
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Quasicentroid Molecular Dynamics
… 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 decoherence. As it relies on purely classical mechanics, the theory leads to simulation methods …
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Nonlinear dynamics of a matter-wave soliton in driven potentials
… for high precision inertial and gravitational field sensing. The localised and dynamically robust nature of matter-wave solitons may help overcome limitations such as wavepacket spreading in current atom interferometry experiments. A typical matter-wave interferometer involves a condensate …
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Nonlinear dynamics of a matter-wave soliton in driven potentials
… for high precision inertial and gravitational field sensing. The localised and dynamically robust nature of matter-wave solitons may help overcome limitations such as wavepacket spreading in current atom interferometry experiments. A typical matter-wave interferometer involves a condensate …
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The effects of thermal radiation on dry convection
… atmospheric radiative-convective model via the mean field approximation. In contrast to the stability threshold, the vertical convective heat flux in the weakly nonlinear convecting state turns out to be little affected by the values of viscosity, thermal diffusivity, or radiative damping. …
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