Thèses : « Wave Packet Dynamic »

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CARONE, FABIANI FILIPPO. « Adsorbption and scattering phenomena in materials science ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50846.

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The present work is divided in two part. The first is dedicated to the investigation of the gas-metal interactions, an interesting area in the basic surface science but also in applied one, since it could provide a more efficient way to design corrosion-resistant structural metals. In particular, we concentrate our attention on the study H2S on Fe surface. Experimental studies, of adsorption of H2S on Fe, and first-principle calculations were carried out for these systems, clarifying some important questions, such as adsorption geometry and dissociation pathways for H2S, on the above close-packed metal surfaces. However, real samples will also include a number of defects, in particular step edges where bonding of adsorbates is usually stronger than at facets. It is therefore interesting to investigate adsorption of H2S on a stepped Fe surface, a task which has not been considered yet to the best of our knowledge. In the present work we study the H2S interaction with Fe(310) surfaces by DFT calculations in order to understand the role of step defects in the adsorption properties. We recall that the (310) surface is relatively stable, and its surface energy predicted to be even smaller than that of Fe(110). We do not only obtain the binding sites and adsorption energies of H2S and its components, but we also relate bonding to the detailed features of the localdensity of states (LDOS). The second part of the present thesis is devoted to the dynamics of scattering. Scattering underlies various physical processes in different field of physics, mainly in solid state, as for example in thermoelectricity, about the filtering of hot electrons by defects, or adsorption and desorption by a surface, or in charge injection and field emission trough interface, usually associated with tunneling mechanisms. The recent developments of nanotechnology and the advent of modern high-speed high-density MOS devices, have revived the technological and theoretical interest of the scientific community on the scattering problem and in particular on quantun tunneling mechanism usually associated. Ultrascaled nanometric CMOS compatible single electron transistors (SETs) and single atom trasistors has lead the emergence of density of states graining and fluctuations in the contacts which may determine discretization of energy levels, charge localization at intradopant length scale and selection rules on quantum states in tunnelling. Consequently, the understanding of dependence of charge dynamics, across a barrier, from the initial position constitutes a relevant aspect in such systems. In this work we study the scattering process in the non stationary framework using Gaussian wave packet (GWP) to describe the particle wave function of the system so as to consider the dependence of scattering dynamics from the initial conditions. Through a numerical solution of the Schr¨odinger equation we analyse the evolution of the system calculating the transmission of the scattering GWP as a function of the initial spread and position x(0), and comparing simulated data with theoretical results. By our analysis a new important issue emerges: the time spent by the particle to reach its asymptotic probability to be observed beyond the barrier ( that we call formation time), strongly depends on initial conditions, and in particular on x(0). Finally, to analytically express such a dependence, we propose a semi-classical approximated model in which tf is described as the time spent by a finite support (accounting for the 0.99 of the probability) of the incident wave packet to cross the barrier, namely the time required to locate, in coordinate space, the greatest amount of the GWP’s probability distribution beyond the barrier interface.

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Sundaram, Ganesh. « Wave-packet dynamics in slowly perturbed crystals : gradient corrections and Berry-phase effects / ». Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.

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Hirisave, Shivaram Niranjan. « Attosecond Resolved Electron Wave Packet Dynamics in Helium ». Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293618.

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Electron dynamics in atoms and molecules occurs on a time-scale of attoseconds (10⁻¹⁸s). With the availability of strong field (∼ 10¹²- 10¹³ W cm⁻²) femtosecond (10⁻¹⁵s) laser pulses with electric fields that can reach and exceed the Coulomb field strength experienced by an electron in the ground state of an atom, it is now possible to generate even shorter pulses with durations on the order of attoseconds by the process of high-harmonic generation (HHG). In this dissertation, experiments to study electron dynamics on attosecond time-scales in a helium atom using attosecond pulses generated by HHG will be described. We use extreme-ultraviolet (XUV) attosecond pulse trains and strong femtosecond near-infrared (IR) laser pulses to excite and ionize helium atoms. We first discuss an experimental technique that allows us to quantify and reduce the detrimental effects of Gouy phase slip on attosecond XUV-IR experiments. We then discuss our experiments to study the dynamic behavior of electronic states in a strong field modified helium atom where we use attosecond pulses to explore the strong-field modified atomic landscape. Using the Floquet theory to interpret our experimental observations we measure the variation in quantum phase of interferences between different fourier components of Floquet states as the IR intensity is varied and as different ionization channels dominate, in real-time. Next, we briefly discuss quantum interferences between photo-electrons ionized from XUV excited states in helium using an IR field which is polarized orthogonal to the XUV polarization. We observe variation in angular distribution of photo-electrons as a function of XUV-IR time-delay. We then discuss a new technique to measure the time-of-birth of attosecond pulses using XUV+IR photo-ionization in helium as a measurement probe. Finally, experiments to study the evolution of XUV excited wave-packets in helium on a time-scale of 100's of femtoseconds with attosecond resolution will be described.

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Kuijpers, Stephan Robert. « Phonon wave-packet dynamics at modelled grain boundaries ». Kyoto University, 2018. http://hdl.handle.net/2433/235089.

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Han, Alex Chao. « Coherence and control in photo-molecular wave packet dynamics ». Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/53991.

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Wave-mechanical phenomena such as resonance and interference, in both light and matter, are central to the principles of quantum coherent control over molecular processes. Focusing on the dynamical aspects, this dissertation is a compilation of studies on the interaction physics involving wave packets in molecules, the driving light field, and the underlying coherence and control. In each work, we will demonstrate interesting correlations between the properties of a carefully designed excitation light field and desirable outcomes of the molecules quantum dynamics. We will analyze the dynamical effect of a Feshbach resonance in the adiabatic Raman photoassociation for ultracold diatomic molecule formation from ultracold atoms. A narrow resonance is shown to be able to increase the effective number of collisions, in an ultracold atomic gas, that are available for photoassociation. This results in an optimal resonance width much smaller than the atomic collision energy bandwidth, due to the balance between the effective collision rate and single-collision transfer probability. Next, we demonstrate the linear molecular response to high-intensity, broadband, shaped optical fields. We show that this originates from interferences based on intra-pulse Raman excitations, and thus response linearity is not unique to the first-order perturbative limit and can not be used to infer the strength of the field. In the last study, we simulate the stochastic vibrational wave packet and dissociation-flux dynamics in a molecule excited by light with temporal and spectral incoherent properties. Between this case and that using a coherent pulse with the same spectral profile, we compare the vibrational wave functions and the loss of electronic and vibrational coherence, and demonstrate the qualitative difference between coherently and incoherently driven dynamics in molecules.
Science, Faculty of
Physics and Astronomy, Department of
Graduate

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Cao, Qian. « Propagation Dynamics of Spatio-Temporal Wave Packets ». University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1405693684.

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Loreau, Jérôme. « Non-adiabatic wave packet dynamics of the charge transfer and photodissociation processes involving HeH+ ». Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210050.

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In this thesis, we present a theoretical investigation of reactive processes involving the HeH$^+$ molecular ion, with applications in laboratory and astrophysical plasma physics. We consider in particular two processes, which are the charge transfer in H + He$^+$ collisions at low energy from a molecular approach and the photodissociation of HeH$^+$.

At the molecular level, the cross section is the basic quantity that has to be determined in order to achieve an understanding of reactive processes. Its calculation will be based on the description of the reactions using an emph{ab initio}, quantum mechanical approach. In this work, we will rely on the Born-Oppenheimer approximation, which allows the molecular motion to be separated into an electronic and a nuclear motion. The evaluation of cross sections then follows two steps.

The first is the determination of the electronic structure of the molecule. We will calculate the adiabatic potential energy curves of the excited electronic states as well as the dipole matrix elements between these states. The non-adiabatic radial and rotational couplings, which result from the breakdown of the Born-Oppenheimer approximation, are also estimated. The second step is to solve the nuclear motion, which we achieve using a time-dependent method based on the propagation of wave packets on the coupled electronic states.

A particular emphasis will be put on the importance of the excited states and of the non-adiabatic couplings in the description of reactive processes.

In the treatment of the charge transfer reaction between H and He$^+$ in excited states, it is well known that the non-adiabatic radial couplings cannot be neglected. However, we will show that the inclusion of the non-adiabatic rotational couplings is also necessary in order to obtain accurate state-to-state cross sections.

In the description of the photodissociation of HeH$^+$ from its ground state, we will show the influence of the excited states on the rate constant and the role of the non-adiabatic radial couplings in the determination of partial cross sections.

We will also consider the possible astrophysical applications of the first triplet state of HeH$^+$. We will show that this state is metastable by evaluating its lifetime, and calculate the cross sections and rate constants for the photodissociation and radiative association of HeH$^+$ in this state.

Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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Andrianov, Ivan V. « Simulations of ultrafast photoinduced wave packet dynamics in three dimensions ». [S.l. : s.n.], 1999. http://www.diss.fu-berlin.de/2000/17/index.html.

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Fabčič, Tomaž. « Wave packet dynamics in atomic systems and Bose-Einstein condensates ». [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-35951.

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Meinhold, Dirk. « Spatial Dynamics of Wave Packets in Semiconductor Heterostructures ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2005. http://nbn-resolving.de/urn:nbn:de:swb:14-1120744780310-59904.

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This thesis presents the first study of the damping of a Bloch oscillating wave packet by Zener tunneling to above-barrier states [1]. We investigate the time evolution of an below-barrier subband Wannier-Stark wave packet in a strongly coupled GaAs/AlGaAs superlattice (SL) with shallow quantum well barriers by optical interband spectroscopy. We use a sub-100 fs homodyne pump-probe technique which is sensitive to the intraband polarization. The presented experimental data unambiguously show an electric field-dependent continuous decrease of the intraband coherence time. Besides the continuous field-induced damping of the intraband polarization, we observe the signature of resonant Zener tunneling of a Bloch oscillating wave packet between discrete states belonging to below and above-barrier bands. This coupling manifests itself as a revival of the intraband polarization [2]. The experiment is modelled in two aspects. First, in a 1D single-particle calculation the wave functions the BO wave packet is composed of are derived. Here, the inter-subband dynamics are found to be given by the energetic splitting between nearly-degenerate below and above-barrier states. The wave packet tunnels from the below-barrier band to the above-barrier band while remaining coherently oscillating. At this time, it is spatially spread over more than 100 nm...

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Goussev, Arseni. « Dynamics of wave packets in the quantum Lorentz gas ». College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2695.

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Thesis (Ph. D.) -- University of Maryland, College Park, 2005.
Thesis research directed by: Physics. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

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Langham-Lopez, Jordan. « Coherent states and wave packet dynamics for the Bogoliubov-de Gennes equations ». Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/34172/.

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We investigate generalizations of coherent states as a means of representing the dynamics of excitations of the superconducting ground state. We also analyse the propagation of generalized coherent state wave packets under the Bogoliubov-de Gennes Hamiltonian. The excitations of the superconducting ground state are superpositions of electron and hole quasi-particles described by the Bogoliubov-de Gennes equations, that can only exist at energies outside the band gap. A natural generalization relevant to the excitations of the superconducting ground state is the tensor product of canonical and spin coherent states. This state will quickly become de-localized on phase space under evolution by the Bogoliubov-de Gennes Hamiltonian due to the opposite velocities of the quasi-spin components. We therefore define the electron-hole coherent states which remain localised on phase space over longer times. We show that the electron-hole coherent states though entangled retain many defining features of coherent states. We analyse the propagation of both product and electron hole coherent states in a superconductor with a spatially homogeneous superconducting band gap. The dispersion relation indicates that wavepackets defined on the band gap have a zero group velocity, but we will show that interference effects can create states on the band gap that propagate at the Fermi velocity. We also consider the two semiclassical, short wavelength regimes, hbar→0$ and the large Fermi energy limit mu→infinity. In general these limits produce behaviour analogous to the canonical coherent states except for isolated cases. Finally we analyse the dynamics of the Andreev Reflection of a Gaussian wavepacket incident on a discontinuous normal-superconducting interface. We show that restricting the energy bandwidth of the incident state inside the superconducting band gap precludes the wavepacket from fully entering the superconducting region. We again consider the two semiclassical regimes.

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Ghinassi, Paolo [Verfasser]. « Investigating the dynamics of Rossby wave packets using Local Finite Amplitude Wave Activity / Paolo Ghinassi ». Mainz : Universitätsbibliothek Mainz, 2020. http://d-nb.info/120272678X/34.

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Cheng, Xiaolu. « Mixed Quantum/Semiclassical Theory for Small-Molecule Dynamics and Spectroscopy in Low-Temperature Solids ». Thesis, University of Oregon, 2013. http://hdl.handle.net/1794/13001.

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A quantum/semiclassical theory for the internal nuclear dynamics of a small molecule and the induced small-amplitude coherent motion of a low-temperature host medium is developed, tested and applied to simulate and interpret ultrafast optical signals. Linear wave-packet interferometry and time-resolved coherent anti-Stokes Raman scattering signals for a model of molecular iodine in a 2D krypton lattice are calculated and used to study the vibrational decoherence and energy dissipation of iodine molecules in condensed media. The total wave function of the whole model is approximately obtained instead of a reduced system density matrix, and therefore the theory enables us to analyze the behavior and the role of the host matrix in quantum dynamics. This dissertation includes previously published co-authored material.

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Källman, Erik. « Quantum Dynamics Simulations Using the Standard Matching Pursuit Gaussian Wavepacket Method : Practical Considerations ». Thesis, Uppsala universitet, Teoretisk kemi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-228505.

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In any quantum dynamics method that approximates wave functions as a linearly combined basis set, non-orthogonality can be is a problem. It has been proven in previous studies that, by using the most standard form of Matching Pursuit in combination with a Gaussian wave packet ansatz, exact quantum-mechanical correspondence can be obtained for particle tunneling in one and two dimensions. This study is an attempt to prove that this approach can be generally applicable to systems of arbitrary dimension propagating with an an-harmonic potential, and that adaptive initial state sampling can be used to make the method even more computationally efficient.

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Barbier, Maximilien. « Dynamics of matter wave packets in the presence of time-dependent absorption ». Thesis, Northumbria University, 2017. http://nrl.northumbria.ac.uk/32543/.

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Atom-laser interaction is at the heart of the vibrant field of quantum optics. The dynamical properties of a moving atom submitted to a laser radiation are strongly influenced by the position- and time-dependence of the latter. The full physical state of the atom must include information about the centre-of-mass motion and the internal structure of the atom. It is challenging to obtain a complete description of the full state of the atom. However, there exists an alternative approach to the dynamics of an atom in the presence of a laser, which is based on the concept of matter-wave absorption. In this thesis, we theoretically study the nonrelativistic one-dimensional motion of an electrically neutral quantum particle in the presence of a thin time-dependent absorber, representing the laser radiation. Our aim is to better understand the precise connection between time-dependent matter-wave absorption and the interaction between an atom and a localised time-dependent laser. Our analysis is based on two different approaches to the problem. The first one describes the moving atom by a two-level system, and represents the laser radiation by an off-diagonal δ-potential. The second model treats the atom as a structureless particle, and describes the laser by a time-dependent absorbing barrier. While the former model can be derived from first principles, the treatment of the absorbing barrier in the latter model lacks a rigorous quantum mechanical justification. The main outcome of our work is to provide a solid physical ground for the absorber model, by explicitly connecting it to the δ-potential model. We have thus extended the range of theoretical tools useful for investigating the effects of time-dependent laser radiation on quantum matter.

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Couto, Rafael Carvalho. « Coupled electron-nuclear dynamics in inelastic X-ray scattering ». Universidade Federal de Goiás, 2016. http://repositorio.bc.ufg.br/tede/handle/tede/7510.

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Esta tese dedicada a estudos tericos e experimentais de espalhamento ressonante inelstico de raios-X (Resonant inelastic X-ray scattering - RIXS) de molculas de monxido de carbono e gua em fase gasosa. Usando estado da arte clculos ab initio de estrutura eletrnica e formalismo de pacotes de onda dependente do tempo, uma anlise completa dos espectros RIXS experimental dos dois sistemas moleculares foi realizada. Na anlise do CO RIXS, fomos capazes de reproduzir o experimento RIXS com excelente preciso, permitindo uma descrio completa dos espectros experimentais. Interferncia entre diferentes canais RIXS correspondentes disperso via orbitais moleculares ortogonais no estado excitado do CO descrito. Com a ajuda do espectro de alta resoluo e simulaes ab initio, mostramos a quebra da aproximao de Born-Oppenheimer na regio onde estados nais de Rydberg acoplam com o estado nal de valncia. Explicamos a formao de uma caracterstica espectral, que foi atribuda a um nico estado em estudos anteriores. Alm disso, atravs da combinao experimento-teoria, aprimoramos o mnimo do potencial do estado excitado de valncia E 1 , juntamente com o constante de acoplamento entre o estado de valncia e dois estados de Rydberg. A m de estudar a gua, desenvolvemos uma nova abordagem terica para descrever molculas triatmicas atravs do formalismo de propagao de pacote de ondas, que reproduz com grande preciso a estrutura vibracional os espectros experimentais RIXS de alta resoluo, permitindo obter importantes concluses. Ns demonstramos que, devido ao acoplamento dos modos vibracionais e anarmonicidade do potencial no estado fundamental e das superfcies de energia potencial do estados excitados, diferentes estados excitados de camada interna em RIXS podem ser usados como portas para sondar diferentes dinmicas de vibrao e para mapear o potencial do estado fundamental usando modos normais de vibrao molecular. O ajuste dos raios-X acima da ressonncia de absoro permite extrair informaes adicionais sobre o potencial do estado fundamental, devido alta excitao vibracional. Substituio isotpica investigada por meio de simulaes tericas e as importantes caractersticas da dinmica nuclear so discutidas, especialmente para o estado excitado de camada interna dissociativo, onde um chamado pico \atmico " formado. Este recurso crucial para explicar a dinmica nuclear em RIXS da gua. Mostramos o forte potencial de experimentos RIXS de alta resoluo combinados IV com simulaes tericas de alto nvel para estudos avanados de estados moleculares altamente excitados, bem como superfcies de energia potencial do estado fundamental, send utilizada como uma tcnica auxiliar para espectroscopia ptica e infra vermelho.
This Thesis is devoted to theoretical and experimental studies of resonant inelastic X-ray scattering (RIXS) of gas-phase carbon monoxide and water molecules. Using state-of-the-art ab initio electronic structure calculations and a time-dependent wave packet formalism, we make a complete analysis of the experimental RIXS spectra of the two molecular systems. In the CO RIXS analysis, we are able to reproduce the RIXS experiment with an excellent accuracy, allowing for a complete description of all experimental features. Interference between di erent RIXS channels corresponding to the scattering via orthogonal molecular orbitals in the core-excited state of CO is described. With the help of the high-resolution spectrum and extensive ab initio simulations we show the complete breakdown of the Born- Oppenheimer approximation in the region where forbidden nal Rydberg states are mixed with a valence allowed nal state. Here we explain the formation of a spectral feature which was attributed to a single state in previous studies. Moreover, through an experimentaltheoretical combination, we improve the minimum of the valence E 1 excited state, along with the coupling constant between the valence and two Rydberg states. In order to study the water system, we developed a new theoretical approach to describe triatomic molecules through the wave packet propagation formalism, which reproduces with high accuracy the vibrational structure of the high-resolution experimental quasi-elastic RIXS spectra, allowing to draw several important conclusions. We demonstrate that due to the vibrational mode coupling and anharmonicity of the ground and core-excited potential energy surfaces, di erent core-excited states in RIXS can be used as gates to probe di erent vibrational dynamics and to map the ground state potential using molecular vibrational normal modes. Tuning the X-rays above the absorption resonance allows to extract additional information about the ground state potential, due to high vibrational excitation. Isotopic substitution is investigated by theoretical simulations and important dynamical features are discussed, especially for the dissociative core-excited state, where a so-called \atomic" peak is formed. This feature is crucial to explain the nuclear dynamics in RIXS from water. We show the strong potential of high-resolution RIXS experiments combined with high-level theoretical simulations for advanced studies of highly excited molecular states, as well as of ground state potential energy surfaces, as an auxiliary technique to optical and IR spectroscopy.

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Whitfield, A. J. « Nonlinear dynamics of wave packets within the framework of the Ostrovsky equation and its generalisations ». Thesis, University College London (University of London), 2016. http://discovery.ucl.ac.uk/1516052/.

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The long-time effect of weak rotation on an internal solitary wave is the decay into inertia-gravity waves and the eventual emergence of a coherent, steadily propagating, nonlinear wavepacket. There is currently no entirely satisfactory description of the wavepacket dynamics or why they form. This thesis examines the initial value problem within the context of the Ostrovsky, or rotation-modified KdV, equation. The linear Ostrovsky equation has maximum group velocity at a critical wave number, often called the zero-dispersion point. This point divides the spectrum into regions of modulational stability and instability, differing from the KdV equation for which the whole spectrum is stable. The flow evolutions are described in the regimes of relatively-strong and relatively-weak rotational effects. When rotational effects are relatively strong it is shown a soliton solution of the nonlinear Schrodinger equation accurately predicts the shape, and phase and group velocities of the wavepackets. In the strong rotation limit it is suggested that these wavepacket solitons form from an instability in the inertia-gravity wavetrain radiated when a KdV solitary wave rapidly adjusts to the presence of strong rotation. When rotational effects are relatively weak the initial KdV solitary wave remains coherent longer, decaying only slowly due to weak radiation and modulational instability is no longer relevant. Wavepacket solutions in this regime appear to be modulated, nonlinear cnoidal waves. A set of perturbed Whitham modulation equations are derived. When rotational effects are relatively weak it is shown the wavepackets are described by cnoidal wavepacket solutions of the perturbed modulation equations.

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Kovac, Philip. « Exploring time-dependent approaches towards the calculation of dynamics and spectroscopic signals : A mixed quantum/semiclassical wave packet method and the theory of transient absorption and femtosecond stimulated Raman scattering ». Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23124.

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We present a time-dependent mixed quantum/semiclassical approach to calculating linear absorption spectra. Applying Variational Fixed Vibrational Basis/Gaussian Bath theory (FVB/GB) to the treatment of small molecules isolated in an extended cryogenic medium, an assumed time-scale separation between the few rapid, largely intramolecular modes of the guest and the several slower extended modes of the medium is utilized to partition a system from the surrounding bath. The system dynamics are handled with basis set methods, while the bath degrees of freedom are subject to a semiclasscial thawed Gaussian ansatz. The linear absorption spectrum for a realistic model system is calculated using FVB/GB results and then compared with a numerically exact calculation. Also contained in this dissertation are previously published theoretical works on Transient Absorption and Femtosecond Stimulated Raman Spectroscopy. Both encompass a rebuilding of the theory and elucidate the information content of the respective spectroscopic signals. This dissertation includes previously published co-authored material.

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Latka, Tobias Thomas [Verfasser], Reinhard [Akademischer Betreuer] Kienberger, Andreas [Gutachter] Bausch et Reinhard [Gutachter] Kienberger. « Few-Femtosecond Nuclear Wave Packet Dynamics in Ozone / Tobias Thomas Latka ; Gutachter : Andreas Bausch, Reinhard Kienberger ; Betreuer : Reinhard Kienberger ». München : Universitätsbibliothek der TU München, 2018. http://d-nb.info/1153545918/34.

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Latka, Tobias Thomas Verfasser], Reinhard [Akademischer Betreuer] [Kienberger, Andreas [Gutachter] Bausch et Reinhard [Gutachter] Kienberger. « Few-Femtosecond Nuclear Wave Packet Dynamics in Ozone / Tobias Thomas Latka ; Gutachter : Andreas Bausch, Reinhard Kienberger ; Betreuer : Reinhard Kienberger ». München : Universitätsbibliothek der TU München, 2018. http://nbn-resolving.de/urn:nbn:de:bvb:91-diss-20180208-1421325-1-9.

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Hashemloo, Avazeh. « Numerical simulation of the dynamics of a trapped molecular ion ». Doctoral thesis, Umeå universitet, Institutionen för fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-118899.

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This thesis explores the dynamics of a heteronuclear diatomic molecular ion, possessing a permanent electric dipole moment, µ, which is trapped in a linear Paul trap and can interact with an off-resonance laser field. To build our model we use the rigid-rotor approximation, where the dynamics of the molecular ion are limited to its translational and rotational motions of the center-of-mass. These dynamics are investigated by carrying out suitable numerical calculations. To introduce our numerical methods, we divide our research topic into two different subjects. First, we ignore the rotational dynamics of the ion by assuming µ = 0. By this assumption, the system resembles an atomic ion, which mainly exhibits translational motion for its center of the mass when exposed to an external trapping field. To study this translational behavior, we implement full-quantum numerical simulations, in which a wave function is attributed to the ion. Finally, we study the quantum dynamics of the mentioned wave packet and we compare our results with those obtained classically. In the latter case, we keep the permanent dipole moment of the ion and we study the probable effects of the interaction between the dipole moment and the trapping electric field, on both the translational and the rotational dynamics of the trapped molecular ion. In order to study these dynamics, we implement both classical and semi-classical numerical simulations. In the classical method, the rotational and the translational motions of the center of mass of the ion are obtained via classical equations of motion. On the other hand, in the semi-classical method, while the translational motion of the center-of-mass is still obtained classically, the rotation is treated full-quantum mechanically by considering the rotational wave function of the ion. In the semi-classical approach, we mainly study the probable couplings between the rotational states of the molecular ion, due to the interaction of the permanent dipole moment with the trapping electric field. In the end, we also present a semi-classical model, where the trapped molecular ion interacts with an off-resonance laser field.

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Brinne, Roos Johanna. « Electron Recombination with Small Molecular Ions ». Licentiate thesis, Stockholm : Bioteknologi, Kungliga Tekniska högskolan, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4375.

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Junginger, Marco Andrej [Verfasser], et Jörg [Akademischer Betreuer] Main. « Transition state theory for wave packet dynamics and its application to thermal decay of metastable nonlinear Schrödinger systems / Marco Andrej Junginger. Betreuer : Jörg Main ». Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2014. http://d-nb.info/1056910429/34.

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Troppmann, Stephanie [Verfasser], Caroline [Akademischer Betreuer] [Gutachter] Lasser, George A. [Gutachter] Hagedorn et Alain [Gutachter] Joye. « Non-Hermitian Schrödinger dynamics with Hagedorn’s wave packets / Stephanie Troppmann ; Gutachter : Caroline Lasser, George A. Hagedorn, Alain Joye ; Betreuer : Caroline Lasser ». München : Universitätsbibliothek der TU München, 2017. http://d-nb.info/1139493124/34.

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Krückl, Viktor [Verfasser], et Klaus [Akademischer Betreuer] Richter. « Wave packets in mesoscopic systems : From time-dependent dynamics to transport phenomena in graphene and topological insulators / Viktor Krückl. Betreuer : Klaus Richter ». Regensburg : Universitätsbibliothek Regensburg, 2013. http://d-nb.info/1034198378/34.

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Chapman, Craig Thomas 1980. « Vibrational wave packets : Molecular state reconstruction in the gas phase and mixed quantum/semiclassical descriptions of small-molecule dynamics in low-temperature solid media ». Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10584.

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xiv, 195 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
We explore the reconstruction of B-state vibrational wave packets in I 2 from simulated two-color nonlinear wave packet interferometry data. As a simplification of earlier proposals, we make use of different vibrational energy ranges in the B-state--rather than different electronic potential surfaces--for the short-pulse preparation and propagation of both target and reference wave packets. Numerical results from noisy interferograms indicate that experimental reconstruction should be possible with high fidelity (>0.99). Time-resolved coherent nonlinear optical experiments on small molecules in low-temperature host crystals are exposing valuable information on quantum mechanical dynamics in condensed media. We make use of generic features of these systems to frame two simple, comprehensive theories that will enable the efficient calculation of their ultrafast spectroscopic signals and support their interpretation in terms of the underlying chemical dynamics. Both treatments rely on the identification of normal coordinates to unambiguously partition the well-structured guest-host complex into a system and a bath and expand the overall wave function as a sum of product states between fully anharmonic vibrational basis states for the system and approximate Gaussian wave packets for the bath degrees of freedom. The theories exploit the fact that ultrafast experiments typically drive large-amplitude motion in a few intramolecular degrees of freedom of higher frequency than the crystal phonons, while these intramolecular vibrations indirectly induce smaller-amplitude--but still perhaps coherent--motion among the lattice modes. The equations of motion for the time-dependent parameters of the bath wave packets are fairly compact in a fixed vibrational basis/Gaussian bath (FVB/GB) approach. An alternative adiabatic vibrational basis/Gaussian bath (AVB/GB) treatment leads to more complicated equations of motion involving adiabatic and nonadiabatic vector potentials. Numerical tests of the FVB/GB are presented. We consider two bilinearly coupled harmonic oscillators with varying coupling strengths and initial conditions and show that the mixed quantum/semiclassical theory compares favorably with the exact results. Linear absorption spectra and wave-packet interferometry signals calculated using the theory are presented. This dissertation includes previously published coauthored material.
Committee in charge: David Herrick, Chairperson, Chemistry; Jeffrey Cina, Advisor, Chemistry; Thomas Dyke, Member, Chemistry Michael Kellman, Member, Chemistry; Hailin Wang, Outside Member, Physics

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Grüner, Barbara, Martin Schlesinger, Philipp Heister, Walter T. Strunz, Frank Stienkemeier et Marcel Mudrich. « Vibrational relaxation and dephasing of Rb2 attached to helium nanodroplets ». Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138750.

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The vibrational wave-packet dynamics of diatomic rubidium molecules (Rb2) in triplet states formed on the surface of superfluid helium nanodroplets is investigated both experimentally and theoretically. Detailed comparison of experimental femtosecond pump–probe spectra with dissipative quantum dynamics simulations reveals that vibrational relaxation is the main source of dephasing. The rate constant for vibrational relaxation in the first excited triplet state 13Σ+g is found to be constant γ ≈ 0.5 ns−1 for the lowest vibrational levels v [less, similar] 15 and to increase sharply when exciting to higher energies
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich

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Grüner, Barbara, Martin Schlesinger, Philipp Heister, Walter T. Strunz, Frank Stienkemeier et Marcel Mudrich. « Vibrational relaxation and dephasing of Rb2 attached to helium nanodroplets ». Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27778.

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The vibrational wave-packet dynamics of diatomic rubidium molecules (Rb2) in triplet states formed on the surface of superfluid helium nanodroplets is investigated both experimentally and theoretically. Detailed comparison of experimental femtosecond pump–probe spectra with dissipative quantum dynamics simulations reveals that vibrational relaxation is the main source of dephasing. The rate constant for vibrational relaxation in the first excited triplet state 13Σ+g is found to be constant γ ≈ 0.5 ns−1 for the lowest vibrational levels v [less, similar] 15 and to increase sharply when exciting to higher energies.
Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

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30

Thiem, Stefanie. « Electronic and Photonic Properties of Metallic-Mean Quasiperiodic Systems ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-83831.

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Understanding the connection of the atomic structure and the physical properties of materials remains one of the elementary questions of condensed-matter physics. One research line in this quest started with the discovery of quasicrystals by Shechtman et al. in 1982. It soon became clear that these materials with their 5-, 8-, 10- or 12-fold rotational symmetries, which are forbidden according to classical crystallography, can be described in terms of mathematical models for nonperiodic tilings of a plane proposed by Penrose and Ammann in the 1970s. Due to the missing translational symmetry of quasicrystals, till today only finite, relatively small systems or periodic approximants have been investigated by means of numerical calculations and theoretical results have mainly been obtained for one-dimensional systems. In this thesis we study d-dimensional quasiperiodic models, so-called labyrinth tilings, with separable Hamiltonians in the tight-binding approach. This method paves the way to study higher-dimensional, quantum mechanical solutions, which can be directly derived from the one-dimensional results. This allows the investigation of very large systems in two and three dimensions with up to 10^10 sites. In particular, we contemplate the class of metallic-mean sequences. Based on this model we focus on the electronic properties of quasicrystals with a special interest on the connection of the spectral and dynamical properties of the Hamiltonian. Hence, we investigate the characteristics of the eigenstates and wave functions and compare these with the wave-packet dynamics in the labyrinth tilings by numerical calculations and by a renormalization group approach in connection with perturbation theory. It turns out that many properties show a qualitatively similar behavior in different dimensions or are even independent of the dimension as e.g. the scaling behavior of the participation numbers and the mean square displacement of a wave packet. Further, we show that the structure of the labyrinth tilings and their transport properties are connected and obtain that certain moments of the spectral dimensions are related to the wave-packet dynamics. Besides this also the photonic properties are studied for one-dimensional quasiperiodic multilayer systems for oblique incidence of light, and we show that the characteristics of the transmission bands are related to the quasiperiodic structure
Eine der elementaren Fragen der Physik kondensierter Materie beschäftigt sich mit dem Zusammenhang zwischen der atomaren Struktur und den physikalischen Eigenschaften von Materialien. Eine Forschungslinie in diesem Kontext begann mit der Entdeckung der Quasikristalle durch Shechtman et al. 1982. Es stellte sich bald heraus, dass diese Materialien mit ihren laut der klassischen Kristallographie verbotenen 5-, 8-, 10- oder 12-zähligen Rotationssymmetrien durch mathematische Modelle für die aperiodische Pflasterung der Ebene beschrieben werden können, die durch Penrose und Ammann in den 1970er Jahren vorgeschlagen wurden. Aufgrund der fehlenden Translationssymmetrie in Quasikristallen sind bis heute nur endliche, relativ kleine Systeme oder periodische Approximanten durch numerische Berechnungen untersucht worden und theoretische Ergebnisse wurden hauptsächlich für eindimensionale Systeme gewonnen. In dieser Arbeit werden d-dimensionale quasiperiodische Modelle, sogenannte Labyrinth-Pflasterungen, mit separablem Hamilton-Operator im Modell starker Bindung betrachtet. Diese Methode erlaubt es, quantenmechanische Lösungen in höheren Dimensionen direkt aus den eindimensionalen Ergebnissen abzuleiten und ermöglicht somit die Untersuchung von sehr großen Systemen in zwei und drei Dimensionen mit bis zu 10^10 Gitterpunkten. Insbesondere betrachten wir dabei quasiperiodische Folgen mit metallischem Schnitt. Basierend auf diesem Modell befassen wir uns im Speziellen mit den elektronischen Eigenschaften der Quasikristalle im Hinblick auf die Verbindung der spektralen und dynamischen Eigenschaften des Hamilton-Operators. Hierfür untersuchen wir die Eigenschaften der Eigenzustände und Wellenfunktionen und vergleichen diese mit der Dynamik von Wellenpaketen in den Labyrinth-Pflasterungen basierend auf numerischen Berechnungen und einem Renormierungsgruppen-Ansatz in Verbindung mit Störungstheorie. Dabei stellt sich heraus, dass viele Eigenschaften wie etwa das Skalenverhalten der Partizipationszahlen und der mittleren quadratischen Abweichung eines Wellenpakets für verschiedene Dimensionen ein qualitativ gleiches Verhalten zeigen oder sogar unabhängig von der Dimension sind. Zudem zeigen wir, dass die Struktur der Labyrinth-Pflasterungen und deren Transporteigenschaften sowie bestimmte Momente der spektralen Dimensionen und die Dynamik der Wellenpakete in Beziehung zueinander stehen. Darüber hinaus werden auch die photonischen Eigenschaften für eindimensionale quasiperiodische Mehrschichtsysteme für beliebige Einfallswinkel untersucht und der Verlauf der Transmissionsbänder mit der quasiperiodischen Struktur in Zusammenhang gebracht

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Rutz, Soeren et Luebeck. « Femtosekundenspektroskopie zur Wellenpaketdynamik in Alkalidimeren und ». Phd thesis, 2000. http://www.diss.fu-berlin.de/2000/127/index.html.

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Pettey, Lucas Richard 1974. « Quantum dynamics on adaptive grids : the moving boundary truncation method ». 2008. http://hdl.handle.net/2152/18283.

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A novel method for integrating the time-dependent Schrödinger equation is presented. The moving boundary truncation (MBT) method is a time-dependent adaptive method that can significantly reduce the number of grid points needed to perform accurate wave packet propagation while maintaining stability. Hydrodynamic quantum trajectories are used to adaptively define the boundaries and boundary conditions of a fixed grid. The result is a significant reduction in the number of grid points needed to perform accurate calculations. A variety of model potential energy surfaces are used to evaluate the method. Excellent agreement with fixed boundary grids was obtained for each example. By moving only the boundary points, stability was increased to the level of the full fixed grid. Variations of the MBT method are developed which allow it to be applied to any potential energy surface and used with any propagation method. A variation of MBT is applied to the collinear H+H₂ reaction (using a LEPS potential) to demonstrate the stability and accuracy. Reaction probabilities are calculated for the three dimensional non-rotating O(³P)+H₂ and O(³P)+HD reactions to demonstrate that the MBT can be used with a variety of numerical propagation techniques.
text

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Fabčič, Tomaž [Verfasser]. « Wave packet dynamics in atomic systems and Bose-Einstein condensates / vorgelegt von Tomaž Fabčič ». 2008. http://d-nb.info/989894703/34.

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Andrianov, Ivan V. [Verfasser]. « Simulations of ultrafast photoinduced wave packet dynamics in three dimensions / vorgelegt von Ivan Andrianov ». 1999. http://d-nb.info/960673458/34.

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Meinhold, Dirk [Verfasser]. « Spatial dynamics of wave packets in semiconductor heterostructures / vorgelegt von Dirk Meinhold ». 2005. http://d-nb.info/976471914/34.

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36

Hamik, Chad Thomas Steinbock Oliver. « Anomalous dispersion of excitation pulses in the 1,4-cyclohexanedione Belousov-Zhabotinsky reaction ». 2003. http://etd.lib.fsu.edu/theses/available/etd-08112004-123237.

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Thesis (Ph. D.)--Florida State University, 2003.
Advisor: Dr. Oliver Steinbock, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (Aug. 27, 2004). Includes bibliographical references.

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37

Belz, Steffen [Verfasser]. « Laser control of torsional nuclear wave packet dynamics via conical intersections = Laserkontrolle der Torsionsbewegungen von Kernwellenpaketen über konische Durchschneidungen / Steffen Belz ». 2011. http://d-nb.info/1013833171/34.

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Lee, Tsung Yen, et 李宗晏. « I. Tuning the photocycle kinetics of bacteriorhodopsin in lipid nanodiscs II. Applications of the truncated grid method to quantum wave packet dynamics ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/51023186146998407134.

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碩士
國立清華大學
化學系
104
I. Monodisperse lipid nanodisc provides bacteriorhodopsin (bR), a light-driven proton pump membrane protein, excellent aqueous dispersibility and native-mimic lipid bilayer environment. To study the lipid-composition dependence of the photo-cycle kinetics of bR, the monomeric bR was embedded in nanodiscs composed of different ratios of negatively-charged lipids (DMPG, DOPG) to zwitterionic lipids (DMPC, DOPC). The steady-state absorption spectra of light-adapted monomeric bR in nanodiscs composed of different lipid ratios exhibited the conservation of the tertiary structure of embedded bR and the ion-exchange chromatography showed increment on negative surface charge as the content of DOPG or DMPG increased. By utilizing transient absorption spectroscopy to monitor the evolution of photocycle intermediates of bR in nanodisc, the photocycle kinetics of bR was significantly retarded and the transient populations of intermediates N and O were decreased as the content of DMPG or DOPG was reduced. In this work, we not only demonstrated the usefulness of nanodiscs as a membrane mimicking system, but also showed that the surrounding lipids play a crucial role in altering the biological functions, e.g., the ion translocation kinetics of the transmembrane proteins. II. Time-dependent quantum wave packet obtained by solving the time-dependent Schrödinger equation (TDSE) provides theoretical information for quantum phenomena of physical systems. In conventional computational methods, the finite difference method is employed to obtain approximate solutions to the TDSE. In order to improve the numerical algorithm for the TDSE, we develop the truncated grid method to reduce the computational effort by eliminating grid points with extremely low probability densities. By applying the new method to several quantum systems, including the free Guassian wave packet and the coherent state of the harmonic oscillator, the propagation behavior of wavepacket were demonstrated. In addition, we employ the truncated grid method to solve the imaginary-time Schrödinger equation for the ground and first-excited states of the harmonic oscillator, the double well potential, and the Morse potential. Excellent computational results for these examples show that the truncated grid method significantly reduces the computational effort relative to the full-grid integration for the TDSE.

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Thiem, Stefanie. « Electronic and Photonic Properties of Metallic-Mean Quasiperiodic Systems ». Doctoral thesis, 2011. https://monarch.qucosa.de/id/qucosa%3A19673.

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Understanding the connection of the atomic structure and the physical properties of materials remains one of the elementary questions of condensed-matter physics. One research line in this quest started with the discovery of quasicrystals by Shechtman et al. in 1982. It soon became clear that these materials with their 5-, 8-, 10- or 12-fold rotational symmetries, which are forbidden according to classical crystallography, can be described in terms of mathematical models for nonperiodic tilings of a plane proposed by Penrose and Ammann in the 1970s. Due to the missing translational symmetry of quasicrystals, till today only finite, relatively small systems or periodic approximants have been investigated by means of numerical calculations and theoretical results have mainly been obtained for one-dimensional systems. In this thesis we study d-dimensional quasiperiodic models, so-called labyrinth tilings, with separable Hamiltonians in the tight-binding approach. This method paves the way to study higher-dimensional, quantum mechanical solutions, which can be directly derived from the one-dimensional results. This allows the investigation of very large systems in two and three dimensions with up to 10^10 sites. In particular, we contemplate the class of metallic-mean sequences. Based on this model we focus on the electronic properties of quasicrystals with a special interest on the connection of the spectral and dynamical properties of the Hamiltonian. Hence, we investigate the characteristics of the eigenstates and wave functions and compare these with the wave-packet dynamics in the labyrinth tilings by numerical calculations and by a renormalization group approach in connection with perturbation theory. It turns out that many properties show a qualitatively similar behavior in different dimensions or are even independent of the dimension as e.g. the scaling behavior of the participation numbers and the mean square displacement of a wave packet. Further, we show that the structure of the labyrinth tilings and their transport properties are connected and obtain that certain moments of the spectral dimensions are related to the wave-packet dynamics. Besides this also the photonic properties are studied for one-dimensional quasiperiodic multilayer systems for oblique incidence of light, and we show that the characteristics of the transmission bands are related to the quasiperiodic structure.
Eine der elementaren Fragen der Physik kondensierter Materie beschäftigt sich mit dem Zusammenhang zwischen der atomaren Struktur und den physikalischen Eigenschaften von Materialien. Eine Forschungslinie in diesem Kontext begann mit der Entdeckung der Quasikristalle durch Shechtman et al. 1982. Es stellte sich bald heraus, dass diese Materialien mit ihren laut der klassischen Kristallographie verbotenen 5-, 8-, 10- oder 12-zähligen Rotationssymmetrien durch mathematische Modelle für die aperiodische Pflasterung der Ebene beschrieben werden können, die durch Penrose und Ammann in den 1970er Jahren vorgeschlagen wurden. Aufgrund der fehlenden Translationssymmetrie in Quasikristallen sind bis heute nur endliche, relativ kleine Systeme oder periodische Approximanten durch numerische Berechnungen untersucht worden und theoretische Ergebnisse wurden hauptsächlich für eindimensionale Systeme gewonnen. In dieser Arbeit werden d-dimensionale quasiperiodische Modelle, sogenannte Labyrinth-Pflasterungen, mit separablem Hamilton-Operator im Modell starker Bindung betrachtet. Diese Methode erlaubt es, quantenmechanische Lösungen in höheren Dimensionen direkt aus den eindimensionalen Ergebnissen abzuleiten und ermöglicht somit die Untersuchung von sehr großen Systemen in zwei und drei Dimensionen mit bis zu 10^10 Gitterpunkten. Insbesondere betrachten wir dabei quasiperiodische Folgen mit metallischem Schnitt. Basierend auf diesem Modell befassen wir uns im Speziellen mit den elektronischen Eigenschaften der Quasikristalle im Hinblick auf die Verbindung der spektralen und dynamischen Eigenschaften des Hamilton-Operators. Hierfür untersuchen wir die Eigenschaften der Eigenzustände und Wellenfunktionen und vergleichen diese mit der Dynamik von Wellenpaketen in den Labyrinth-Pflasterungen basierend auf numerischen Berechnungen und einem Renormierungsgruppen-Ansatz in Verbindung mit Störungstheorie. Dabei stellt sich heraus, dass viele Eigenschaften wie etwa das Skalenverhalten der Partizipationszahlen und der mittleren quadratischen Abweichung eines Wellenpakets für verschiedene Dimensionen ein qualitativ gleiches Verhalten zeigen oder sogar unabhängig von der Dimension sind. Zudem zeigen wir, dass die Struktur der Labyrinth-Pflasterungen und deren Transporteigenschaften sowie bestimmte Momente der spektralen Dimensionen und die Dynamik der Wellenpakete in Beziehung zueinander stehen. Darüber hinaus werden auch die photonischen Eigenschaften für eindimensionale quasiperiodische Mehrschichtsysteme für beliebige Einfallswinkel untersucht und der Verlauf der Transmissionsbänder mit der quasiperiodischen Struktur in Zusammenhang gebracht.

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