Literatura científica selecionada sobre o tema "Transfert non adiabatique"
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Artigos de revistas sobre o assunto "Transfert non adiabatique"
Soualmi, Rabiaa, Abderrahmane Benbrik, Mohammed Cherifi, Denis Lemonnier e Siham Laouar-Meftah. "Etude numérique de la convection naturelle dans une enceinte rectangulaire en présence d’un gradient de température et une génération de chaleur interne". Journal of Renewable Energies 21, n.º 3 (30 de setembro de 2018): 403–13. http://dx.doi.org/10.54966/jreen.v21i3.700.
Texto completo da fonteTeses / dissertações sobre o assunto "Transfert non adiabatique"
Posenitskiy, Evgeny. "Dynamique moléculaire non-adiabatique des complexes de type PAH". Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30080.
Texto completo da fontePolycyclic Aromatic Hydrocarbons (PAHs) have been proposed as main carriers of diffuse interstellar bands that are observed in the interstellar medium. This has motivated an extensive study of their photophysical and photochemical response to UV irradiation. Underlying competing mechanisms drive the evolution of gas in the interstellar medium. The main objective of this thesis is to describe and to get theoretical insight in the energy relaxation mechanisms in large PAH molecules via extensive non-adiabatic molecular dynamics simulations coupled to the linear response Time-Dependent Density Functional based Tight Binding (TD-DFTB) approach of the excited states. Prerequisite substantial development was made in the DFTB deMon-Nano package (http://demon-nano.ups-tlse.fr), firstly with the implementation of analytical gradients of potential energy surfaces (PESs) and of non-adiabatic couplings within the TD-DFTB scheme. Next, the Tully's fewest-switches trajectory surface hopping (FSSH) algorithm has been adapted and coupled to the TD-DFTB scheme in order to take into account non-adiabatic transitions. After detailed methodological considerations and comparison with higher-level electronic structure methods, the first full-scale application is dedicated to non-adiabatic molecular dynamics of linearly cata-condensed PAHs. Electronic relaxation from the brightest excited state has been simulated for neutral polyacenes with 2 to 7 aromatic cycles. The results display a striking alternation in decay times of the brightest singlet state computed for polyacenes with up to 6 aromatic cycles, which is correlated with a qualitatively similar alternation of energy gaps between the brightest state and the state lying just below in energy. Next, the influence of geometry on relaxation has been investigated through the comparison of two isomers: armchair-edge chrysene versus zigzag-edge tetracene. After assessing the performance of DFTB parameter sets, the main focus is given to the analysis of the electronic relaxation from the brightest excited state, which is located around 270 nm for both isomers. The results show that the electronic population of the brightest excited state in chrysene decays an order-of-magnitude faster than that in tetracene. This is correlated with a significant difference in energy gaps between the brightest state and the state lying just below in energy, which is consistent with the previous conclusions for polyacenes. A last major development concerns the use of Machine Learning (ML) algorithms that have been proposed as a way to avoid most of the computationally-demanding electronic structure calculations. It aims to assess the performance of neural networks algorithms applied to excited-state dynamics. Electronic relaxation in neutral phenanthrene has been chosen as a test case due to the diversity of available experimental results. Several neural networks have been trained with different parameters and their respective accuracy and efficiency analyzed. In addition, approximate trajectory surface hopping schemes have been interfaced to ML-based PESs and gradients, resulting in non-adiabatic dynamics simulations at a negligible cost. Various simplified hopping approaches have been compared with FSSH. Overall, ML is found to be a highly promising tool for nanosecond-long molecular dynamics in excited states. This PhD research opens new avenues to investigate theoretical photophysics of large molecular complexes. Last but not least, the theoretical tools developed and implemented in deMon-Nano in a modular way can be further combined with other advanced (such as Configuration Interaction) DFTB techniques better adapted to charge-transfer states
Semmar, Nadjib. "Contribution à l'étude thermo-physique des fluides non-newtoniens à l'aide d'un calorimètre adiabatique original". Nancy 1, 1993. http://www.theses.fr/1993NAN10246.
Texto completo da fonteRozsályi, Emese Tünde. "Theoretical study of charge transfer in ion-molecule collisions". Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10152/document.
Texto completo da fonteCollisiosns of slow multiply charged ions with molecular species have been widely investigated in the past few years. Imortant experimental and theoretical effort has been focused on reactions with simple targets. Consideration of more complex molecular targets are now of increasing interest, in particular with regardto possible direect or indirect processes occuring in the irradiation of the biological medium.. In these reactions generally at relativity low energies, different processes have to be considered: exitation and fragmentation on the molecule, ionization of the gaseous target, and also possible charge transfer from the multicharged ion toward the biomolecule..Charge transfer can be investigated theoretically in the framework of the molecular representation of the collision. Such studies provides important information on the mecanism as well as on the electronic structure of the projectile and target during the reaction. The charge-transfer process in collisions on C2+ ions with hydrogen halide molecule (HF, HCI) has been studied by means of ab initio quantum chemistry molecular methods followed by semiclassical dynamical treatment in the keV collision energy range. The mechanism has been investigated in detail in each reaction, in connection with nonadiabatic interactions around avoided crodssings between states involved in the process
Valentin, Constance. "Manipulations non-cohérente et cohérente d'un jet atomique de Césium par laser : mélasses optiques dans un champ magnétique et transfert adiabatique de population". Paris 11, 1994. http://www.theses.fr/1994PA112026.
Texto completo da fonteRozsalyi, Emese Tünde. "Theoretical study of charge transfer in ion-molecule collisions". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-01070739.
Texto completo da fonteKiorpelidis, Ioannis-Markos. "Wave phenomena in one-dimensional space or time varying media". Electronic Thesis or Diss., Le Mans, 2023. https://cyberdoc-int.univ-lemans.fr/Theses/2023/2023LEMA1032.pdf.
Texto completo da fonteThe interaction of waves with media possessing spatial or/and temporal fluctuations leads tointeresting phenomenology. Within this framework, in the present thesis four wave phenomena arestudied: two occurring in spatially-varying media and two in time-varying media. We begin byexploring wave scattering by a finite spatially-periodic setup that is subject to perturbation. Ourfocus is on perfect transmission resonances (PTRs) and we develop a method for preserving themunder asymmetric perturbations. The performed analysis reveals a pairwise connection betweenPTRs of a spatially-periodic scattering setup with mirror symmetric cells. In the same contextof spatially varying media, we compute the localization length of the topological edge modes thatare supported in a mechanical mass-spring chain possessing random fluctuations of its stiffnessparameters. In the presence of strong chiral disorder the localization length diverges, implying atopological phase transition that is induced purely by disorder. As a next step we consider thecase where the couplings of the mechanical mass-spring chain vary with time in a deterministicway. Then this time-varying system can serve as a platform for transferring a topological edgemode. Going beyond the adiabatic limit, we design a protocol for the time-varying couplingsthat results in a fast and robust transfer and even more leads to amplification of the transferrededge mode. To shed light into the phenomenon of amplification in a time-varying platform, weexplore the propagation of a wave in a medium with time-periodic refractive index and with wavedynamics governed by the Mathieu equation. The wave exhibits transient amplification due to thenon normal nature of the propagator matrix and we provide numerical evidence that the globalamplifying features are provided merely by the monodromy matrix
Ho, Emmeline. "Vers un modèle vibronique innovant pour les hydrocarbures conjugués". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS087/document.
Texto completo da fonteThe present work is focused on the rationalization of the excitation transfer mechanism in polyphenylene ethynylenes (PPEs). A static study was performed using TDDFT, allowing to confirm both the localization of the excited states of meta-PPEs on para building blocks and the hierarchy in the interactions governing the photochemical properties of PPEs. Conical intersections were identified, along with few components of their branching spaces. Studying those supported the assumption of an energy transfer proceeding through internal conversion between excited states localized on different building blocks.In addition, we proposed a multiscale vibronic model for the energy of the eletronic states. In particular, we expressed the energies of the frontier orbitals of PPEs in terms of the energies of the frontier orbitals of benzene and acetylene, using an effective Hückel-type Hamiltonian. Perfoming different optimizations, we achieved to propose an expression for the energy of the electronic transition in terms of a reduced number of local nuclear coordinates
Rabli, Djamal. "Extension de la méthode du potentiel modèle pour traiter la dynamique des systèmes moléculaires à couches ouvertes : applications : au transfert de charge dans les collisions entre Si3+ et He et entre He2+ et He métastable, à la détermination des potentiels adiabatiques Li2". Paris 6, 2001. http://www.theses.fr/2001PA066564.
Texto completo da fonteFernandez, José Manuel. "De computatione quantica". Thèse, 2003. http://hdl.handle.net/1866/14546.
Texto completo da fonte