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 76 for “"Quantum dynamics"”.
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Theoretical Studies of Quantum Dynamics
Using the FPF method, we have carried out accurate path integral simulations of the primary charge separation in bacterial photosynthesis. The process is modeled in terms of three coupled electronic states corresponding to the photoexcited special pair, the reduced accessory bacteriochlorophyll and …
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WAVEPACKET APPROACHES TO DISSIPATIVE QUANTUM DYNAMICS
… arising in Chemistry, Physics and Biology show quantum effects. Representative examples are chemical reactions involving light atoms, energy transfer in complex environments, electronic and geometrical properties of complex and bulk systems, tunneling phenomena etc. Theoretical Chemistry deals …
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Iterative Monte Carlo for quantum dynamics
… an exact path integral methodology for computing quantum dynamical information. This method combines the concepts of iterative propagation with the features of Monte Carlo sampling. The stepwise evaluation of the path integral circumvents the growth of statistical error with time and the use of …
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The semiclassical limit of quantum dynamics
We study the ħ→0 limit of the quantum dynamics determined by the Hamiltonian H(ħ) = -(ħ²/2m)Δ + Ｖ on L²(ℝ<sup>n</sup>) for a large class of potentials. By convolving with certain Gaussian states we obtain classically determined asymptotic behavior of the quantum evolution of states of compact …
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Quantum Dynamics With Classical and Quantum Trajectories
The forward-backward semiclassical dynamics (FBSD) approximation provides a rigorous and practically useful methodology for simulating the dynamics of condensed phase systems that exhibit quantum mechanical effects. It is shown that FBSD autocorrelation functions of momentum and position-dependent …
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Anomalous quantum dynamics in scarred and integrable systems
Generic quantum systems are expected to reach local thermal equilibrium under their unitary dynamics starting from any initial state. This thesis presents scenarios in which such thermalization does not occur. Firstly, we establish the quantum integrability of the central spin-1 XX model by …
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Quantum Dynamics of Strong Field Light-Matter Interactions
… insights into long-debated problems related to quantum tunneling, namely, the quantum tunneling time and momentum i.e., the ongoing debate in the literature about how much time a particle spends in the classically forbidden region during the tunneling process and what is its momentum when it …
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Theoretical methods for the study of quantum dynamics
… theoretical methods for the computation of quantum dynamical quantities are formulated, implemented, and applied, in the overall context of overcoming the exponential scaling property of quantum mechanics. The convergence of the approximate forward-backward semiclassical dynamics (FBSD) …
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Path integral methods for quantum dynamics in condensed phases
Quantum mechanical effects play an important role in dynamics of condensed phases. It is also well known that the difficulty of solving the full Schrödinger equation grows exponentially with time. One approach to cope up with this difficulty is to restrict quantum treatment to a few particles …
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Phase space and path integral approaches to quantum dynamics
"Exact quantum dynamical simulation of processes in highly coupled condensed phase reactions is extremely challenging. The work reported in this dissertation builds on top of two different approaches. First, we present methods for calculating the multidimensional Wigner function. We start with a …
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Quantum dynamics of 2D antiferromagnets: predictions from theory and machine learning
Contains fulltext : 250503.pdf (Publisher’s version ) (Open Access)
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An Analysis of Three Path-Integral Based Approximations to Quantum Dynamics
… is a challenging problem, especially when the dynamics of the atomic nuclei need to be treated quantum mechanically. In this thesis we analyse three path-integral based approximations for computing quantum time-correlation functions: constant-uncertainty molecular dynamics (CUMD), the fitted …
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Quantum Dynamics of Strongly-Interacting Bosons in Optical Lattices with Disorder
… lattices offer an important tool for studying dynamics in many-body interacting systems in a pristine environment. This thesis focuses on three theoretical works motivated by recent optical lattice experiments. In the first, we theoretically study the center of mass dynamics of states derived …
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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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Quantum dynamics in the condensed phase: path integrals, master equations and purity
Rigorous approaches to the dynamics of quantum systems in large dissipative environments are extremely challenging, owing to the well-known exponential scaling. The work reported here builds up on existing highly accurate methods developed in our group, namely the quasi-adiabatic propagator (QuAPI) …
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Quantum dynamics in laser–assisted collisions, laser–molecule interactions, and particle–surface scattering
The time-dependent Schrödinger equation is integrated on a numerical lattice for up to three-dimensional problems. The wave packet propagation technique has been applied to ion – atom collisions in a strong laser field, the vibrational nuclear motion in small homonuclear diatomic molecular ions, …
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Atomistic quantum dynamics: implementation and applications of the quantum-classical path integral method
… can be hampered by the need for both a quantum mechanical treatment for the reactive degrees of freedom, along with a classical description of the environment, since it is typically too complex for quantum dynamical simulation to be feasible. To address these difficulties, a number of …
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Quantum Dynamics of Small Josephson Junctions: An Application to Superconductivity in Granular Films
This thesis is devoted to a study of the quantum dynamics of small Josephson junctions. Of interest are those features of the junction's behavior which depend explicitly on the quantum mechanical nature of the phase difference (phi) between the superconductors.
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Quantum dynamics of small Josephson junctions: an application to superconductivity in granular films
This thesis is devoted to a study of the quantum dynamics of small Josephson junctions. Of interest are those features of the junction's behavior which depend explicitly on the quantum mechanical nature of the phase difference <1> between the superconductors. In Chapters I and IT several …
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Spectral gaps for many-particle systems, semiclassical analysis of graphene, and quantum dynamics
… this thesis are within the field of mathematical quantum mechanics and investigate theoretical problems as well as computational problems for (non)-linear Schrödinger equations: The first two results, presented in the first chapter, are concerned with spectral gaps of classical many-particle …
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