Tesi sul tema "Méthode d'approximation Hartree-Fock"
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Trabelsi, Saber. "Analysis of the MultiConfiguration Time-Dependent Hartree-Fock equations". Paris 7, 2008. http://www.theses.fr/2008PA077117.
Testo completoThe multiconfiguration methods are a natural improvement of well-known simple models for approximating the linear N body Schro}dinger equation for atomic and molecular Systems with binary - Coulomb in realistic situations- interactions, like the Hartree and the Hartree-Fock equation. Models like MCTDHF are intensively used for numerical simulations in quantum physics/chemistry. However, from the mathematical point of view, these equations are yet poorly understood. The present contribution gives the first rigorous mathematical foundation of the MCTHDH(F) equations with the singular Coulomb interaction. In particular, we formulate in a convenient way for the mathematical analysis the associated initial value problem for which we obtain well-posedness results depending on the regularity of the initial data, with and without an assumption on the rank of the associated density matrix. Also, numerical simulations of a toy model are presented with particular interest to the so called « correlation » which is one of the main motivations and advantage of the multiconfiguration methods compared to Hartree-Fock models
Léon, Jean-François. "Etudes mathématiques de quelques problèmes issus de la physique". Paris 9, 1990. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1990PA090013.
Testo completoArvanitis, Christos. "Méthodes variationnelles-perturbatives en théorie quantique des champs". Aix-Marseille 2, 1993. http://www.theses.fr/1993AIX22059.
Testo completoOuazzani-Taïb, Taïeb. "Calcul ab initio Hartree-Fock de la structure géométrique et électronique de surfaces de chalcogénures alcalins et alcalino-terreux : approche de l'hydrogène atomique". Pau, 1995. http://www.theses.fr/1995PAUU3001.
Testo completoCatto, Isabelle. "Analyse mathématique de modèles de la mécanique quantique". Paris 9, 1992. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1992PA090005.
Testo completoRoques, Jérôme. "Modélisation de l'adsorption dissociative de molécules diatomiques sur des agrégats métalliques par la méthode de la fonctionnelle de la densité : comparaison avec les propriétés du massif et de la surface infinie". Toulouse, INPT, 2001. http://www.theses.fr/2001INPT010G.
Testo completoSmet, Françoise. "Sur la théorie des équations de Hartree-Fock dépendant du temps : application au calcul des tenseurs d'hyperpolarisabilité". Lille 1, 1987. http://www.theses.fr/1987LIL10222.
Testo completoAzavant, Patrick. "Approche théorique de la diffusion élastique et inélastique dans les solides par la méthode AB initio Hartree-Fock : application aux sulfures de lithium et de sodium". Pau, 1994. http://www.theses.fr/1994PAUU3005.
Testo completoChatillon, Audrey. "Spectroscopie des transfermiums impairs en proton : la structure du noyau de 251 Md". Lyon 1, 2005. http://www.theses.fr/2005LYO10179.
Testo completoBoutassetta, Nabil. "Prédiction théorique de la structure électronique de molécules diatomiques comportant un alcalino-terreux". Lyon 1, 1997. http://www.theses.fr/1997LYO10127.
Testo completoLembarki, Abderrahim. "Développement de fonctionnelles corrigées du gradient en théorie de la fonctionnelle de la densité". Lyon 1, 1994. http://www.theses.fr/1994LYO10340.
Testo completoBaranek, Philippe. "Approche ab initio des propriétés dynamiques en milieu cristallin : constantes élastiques et phonons Mg2Si, transitions de phase dans KNbO3". Lille 1, 1998. https://pepite-depot.univ-lille.fr/LIBRE/Th_Num/1998/50376-1998-175.pdf.
Testo completoBaudouin, Lucie Coline. "Contributions à l'étude de l'équation de Schrödinger : problème inverse en domaine borné et contrôle optimal bilinéaire d'une équation de Hartree-Fock". Versailles-St Quentin en Yvelines, 2004. http://www.theses.fr/2004VERS0006.
Testo completoThis thesis deals with some properties of the time dependent Schrödinger equation. On the one hand, we study the inverse problem in a bounded domain of determining the potential from measurements of the normal derivative of the solution through a part of the boundary. On the other hand, we prove the existence of a unique solution of a Schrödinger equation with coulombian potential, locally singular, and electric unbounded potential, both depending on space and time variables. We then study the system coupling the corresponding Hartree-Fock equation with classical newtonian dynamics. Eventually, we consider bilinear optimal control problems of the solution of these last equations, the control being performed by the external electric potential. We prove the existence of optimal controls and give optimality conditions in the suitable cases
Simenel, Cédric. "Dynamique nucléaire autour de la barrière : de la fusion à l'évaporation". Phd thesis, Université de Caen, 2003. http://tel.archives-ouvertes.fr/tel-00003142.
Testo completoBertrand, Thierry. "Approximation des phases aléatoires self-consistante appliquée à un modèle schématique de la théorie des champs". Lyon 1, 1998. http://www.theses.fr/1998LYO10292.
Testo completoKempf, Jean-Yves. "Détermination des propriétés électroniques des oxydes de métaux de transition à base de vanadium". Nancy 1, 1995. http://www.theses.fr/1995NAN10194.
Testo completoBoutou, Véronique. "Structures et propriétés électroniques de petits agrégats de baryum nus et oxygénés". Lyon 1, 1996. http://www.theses.fr/1996LYO10301.
Testo completoCastellano, Olga. "Etudes théoriques des propriétés optiques non linéaires d'anions aromatiques et de leurs complexes organométalliques". Angers, 2005. http://www.theses.fr/2005ANGE0029.
Testo completoWe study theoretically the optical properties (, , ) of a series of aromatic anions of the S-, , and substituent groups, with n = 1, 2, 3 benzene rings, by using PM3 parametrization, Ab Initio at Hartree-Fock HF, M¢ller-Plesset MP2 and MP4 levels, and DFT methods at B3LYP level with the 6-31+G(d,p) and 6-311++G(3d,3p) basis sets. The dynamic properties where also evaluated with the Time Dependent Hartree-Fock (TDHF). Coupled Clusters CC methods were used for the benzene-thiolate anion properties only. Additionally, the nonlinear properties at PM3 level of some organometallic thiolates complexes: , where M = Zn, Cd,Hg, Pb and m = 3, 4, were also studied. On the other hand, we determined using the hyper Rayleigh-Scattering HRS experimental technique of some new synthesized chiral carboxylates salts using methanol as solvent and we also measured a series of bases of nucleic acid such as uracil, thymine, adenine, cytosine and 5-fluorouracil compounds in water solutions. Also, was studied the first hyperpolarizability of para-Nitroaniline in methanol solution. The experimental results are supported by calculations of the zzz main component associated to the HRS response
Ebran, Jean-Paul. "Description relativiste de l’état fondamental des noyaux atomiques par l’approche du champ moyen auto-cohérent, incluant la déformation et la superfluidité". Paris 11, 2010. http://www.theses.fr/2010PA112352.
Testo completoThe present work deals with the development of a relativistic Hartree-Fock-Bogoliubov approach in axial symmetry (RHFBz). The relevance of a covariant framework is not imposed by the need for relativistic nuclear kinematics. Rather, it is linked to the physics encoded in the Lorentz symmetries. Some nuclear properties naturally emerge in a relativistic approach: spin-orbit potential, pseudo-spin symmetry, nuclear magnetism, saturation mechanism od nuclear matter … Nucleons are treated as Dirac spinor while their in-medium interactions are described through the exchange of effective meson fields. The dynamics of these degrees od freedom is specified by a phenomenological Lagrangian. Its minimization leads to the model equations. The exact treatment of the exchange terms allows to construct a more complete energy density functional in comparison to those involved in RMF (relativistic mean field). It also allows to include the pion degree of freedom, which contributes to the tensor force. The RHFBz approach is illustrated through the description of carbon, neon and magnesium isotopes
Voisin, Christophe. "Contribution au calcul du terme d'induction dans les potentiels d'interactions moléculaires pour la modélisation des polypeptides". Nancy 1, 1991. https://tel.archives-ouvertes.fr/tel-00175114.
Testo completoSieja, Kamila. "Extended approach to correlations beyond mean-field in atomic nuclei". Bordeaux 1, 2007. http://www.theses.fr/2007BOR13352.
Testo completoChabanat, Eric. "Interactions effectives pour des conditions extrêmes d'isospin". Lyon 1, 1995. http://www.theses.fr/1995LYO10016.
Testo completoBerger, Jean François. "Approche microscopique auto-consistante des processus nucléaires collectifs de grande amplitude à basse énergie : application à la diffusion d'ions lourds et à la fission". Paris 11, 1985. http://www.theses.fr/1985PA112268.
Testo completoA theoretical framework and numerical techniques allowing to describe low energy, large amplitude collective phenomena in nuclei from the only data of the nuclear effective interaction is presented. In this method, the collective properties of the system are analyzed with the help of the full Hartree-Fock-Bogolyubov theory and different kinds of constraints acting as external fields. The collective dynamics is then deduced from the self-consistent approach in a completely quantum-mechanical formalism based on the Generator Coordinate prescription and the adiabatic approximation. With this procedure, nuclear structure effects, in particular the influence of pairing correlations on the collective dynamics, are incorporated in a completely microscopic and self-constent way. The applications we present use GOGNY’S D1 effective interaction. Due to the very general parametrization of this force – in particular, its finite range – most known nuclear properties, including those associated to pairing, can be reproduced quantitatively. The ¹²C + ¹²C reaction at low energy is first studied. The position of the two first 0⁺ resonances is consistent with experimental data. The analysis of the wave functions shows that these resonances do not arise from a quasi-molecular ¹²C - ¹²C state. Our approach is then applied to the fission of ²⁴⁰Pu. Potential energy surfaces as functions of elongation, left-right asymmetry and necking-in are displayed. The main known characteristics of these surfaces, in particular fission barrier heights appear to be correctly reproduced. An interpretation for the mechanism of scission and for cold fission events is proposed. A dynamical calculation taking into account the variations of the collective inertia confirms this interpretation and shows that the nuclear evolution between saddle and scissions can be described using the adiabatic approximation
Olbratowski, Przemyslaw. "Chiral and magnetic rotation in atomic nuclei studied within self-consistent mean-field methods". Phd thesis, Université Louis Pasteur - Strasbourg I, 2004. http://tel.archives-ouvertes.fr/tel-00007048.
Testo completoFaes, Jean-Baptiste. "Utilisation d'une interaction nucléon-nucléon de portée finie dans le formalisme du modèle en couches avec couplage aux états du continuum". Caen, 2007. http://www.theses.fr/2007CAEN2010.
Testo completoThe unification of nuclear structure and nuclear reactions was always a great challenge of nuclear physics. Extreme complexity of finite quantum systems lead in the past to a separate development of nuclear structure and nuclear reactions. A unified description of both fields is possible within the continuum shell model. All previous applications of this model used the finite depth local potential to generate the single-particle basis, and the zero-range residual interaction. In the thesis, we have deveoped the continuum shell model formalism for a finite-range nucleon-nucleon interaction and an arbitrary number of nucleons in scattering continuum. The great advantage of the present formulation is the same two-body interaction used both to generate the single-particle basis and to describe couplings to the continuum states. This formulation opens the possibility for an ab initio continuum shell model studies with the single nucleon-nucleon interaction generating the nuclear mean field, the configuration mixing and the coupling to the scattering continuum. First realistic applications of the above model has been shown for spectra of fluorine isotopes and elastic phase-shifts in the reaction 16O(p, p)16O
Dao, Duy Duc. "Approximation de Hartree-Fock pour les noyaux déformés avec un potentiel général à 2-corps et corrélations d'appariement avec une interaction résiduelle cohérente". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0245.
Testo completoIn this work, we have developed the Hartree-Fock (HF) approximation in momentum space for deformed nuclei with a general nucleon-nucleon (NN) potential. The structure of such a potential has been investigated in momentum space from its symmetries. Its constructions has been realized in a tensorial separable momentum-spin-isospin representation. Moreover, to treat low-momentum interactions, we have implemented the Similarity Renormalization Group approach. Three momentum representations have been studied: the plane-wave, the partial-wave and the confined plane-wave. The numerical implementation has been validated against an existing HF-Skyrme code in the harmonic oscillator basis. We have found that the confined plane-wave basis provides many advantages over the two others, namely: flexible construction of symmetry-adapted bases, efficient calculation of matrix elements (nuclear, Coulomb and center of mass kinetic correction) and optimization in ressources (time and memory). This basis is characterized by two parameters: the confinement box size (cube) which can be essentially related to the nuclear radius and a single-particle momentum cut-off which is directly linked to the cut-off in relative momentum of the interaction. Bulk properties of some spherical and deformed even-even nuclei in the mass region A < 100 have been calculated with recently developed NN potentials. The resulting residual interaction has been derived to study pairing correlations within the Highly Truncated Diagonalization Approach (HTDA). In particular, the question of the convergence with the model space has been addressed
Fau, Amélie. "Finite Element Approach of Electronic Structures". Phd thesis, Ecole Centrale Paris, 2012. http://tel.archives-ouvertes.fr/tel-00997398.
Testo completoMassot, Élisabeth. "Description relativiste chirale de la matière nucléaire incluant des effets de confinement du nucléon". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10128/document.
Testo completoThis work aims at constructing a model for symmetric and asymmetric nuclear matter in a relativistic approach including effects from quantum chromodynamics, in particular chiral symmetry and confinement. We consider an assembly of nucleons interacting via meson exchange. The attraction is due to a chiral invariant scalar field associated with the fluctuations of the chiral condensate. The inclusion of scalar nucleonic effects due to the quark substructure of the nucleon ensures the saturation to occur. The parameters corresponding to the scalar sector of the interaction and to the quarks confinement in the nucleon are obtained from lattice calculations. The rest of the parameters are obtained as much as possible by hadron phenomenology. With such constrained inputs, the results are nevertheless very good: this constitutes the originality of this work. In one part, we chood to work at the mean-field level in the Hartree--Fock scheme. The propagation of the scalar field in the Hartree-Fock terms induce some rearrangement effects which play an essential role in the Hugenhotz--Van hove theorem. We discuss also the role of the tensor part of the $\rho$ interaction in the symmetry energy and the isospin dependance of the Landau effective mass. Then, in the idea to enlarge this work to neutron stars, we give the equation of state predicted by our model. The last step corresponds to the introduction of effects after the mean-field including the correlation energy due to pion loops. An important ingredient is the Landau-Migdal parameter controling short range interactions. The correlation energy enhances the description of the saturation point of nuclear matter
David, Grégoire. "Décomposition de l'intéraction d'échange magnétique par l'approche à brisure de symétrie : théorie et applications". Electronic Thesis or Diss., Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0536.
Testo completoThis work is focused on the decomposition of the magnetic exchange coupling (J) between magnetic centers in the broken-symmetry approach. The purpose of this method is to extract from unrestricted calculations the different contributions to the magnetic coupling: the direct exchange (J₀) between the magnetic orbitals, the kinetic exchange interaction (ΔJ_{KE}) allowing the delocalization of the magnetic orbitals and the core polarization (ΔJ_{CP}) of non-magnetic electrons. The first part of this thesis is centered on the theory of the decomposition method in the simplest case of a centro-symmetric system with two electrons in two magnetic centers. The physical meaning is explained in relation with methodological and theoretical tools used in this approach. The second part presents the implementation of the method in the Orca package and its application to non centro-symmetric systems. In particular, this application highlights the interest of a such automatic method in standard quantum package. The last part of this work is focused on the methodological developments carried out during these three years. An innovative method avoiding the spin contamination problem is presented to extract the spin polarization effects. Furthermore, a generalization of the decomposition of J to more complicated systems with more than two electrons in two magnetic centers is discussed. Special attention was given to the explanation and physical meaning of broken symmetry approach in Hartree-Fock and Density Functional Theory
Ducoin, Camille. "Rôle de l'isospin dans la transition de phase liquide-gaz de la matière nucléaire". Caen, 2006. http://www.theses.fr/2006CAEN2028.
Testo completoNuclear matter presents a phase transition of the liquid-gas type. This well-known feature is due to the nuclear interaction profile (mean-range attractive, short-range repulsive). Symmetric nuclear matter thermodynamics is thus analogous to that of a Van der Waals fluid. The study shows up to be more complex in the case of asymmetric matter, composed of neutrons and protons in an arbitrary proportion. Isospin, which distinguishes both constituents, gives a measure of this proportion. Studying asymmetric matter, isospin is an additional degree of freedom, which means one more dimension to consider in the space of observables. The nuclear liquid-gas transition is associated with the multi-fragmentation phenomenon observed in heavy-ion collisions, and to compact-star physics : the involved systems are neutron rich, so they are affected by the isospin degree of freedom. The present work is a theoretical study of isospin effects which appear in the asymmetric-nuclear-matter liquid-gas phase transition. A mean-field approach is used, with a Skyrme nuclear effective interaction. We demonstrate the presence of a first-order phase transition for asymmetric matter, and study the isospin distillation phenomenon associated with this transition. The case of phase separation at thermodynamic equilibrium is compared to spinodal decomposition. Finite size effects are addressed, as well as the influence of the electron gas which is present in the astrophysical context
David, Grégoire. "Décomposition de l'intéraction d'échange magnétique par l'approche à brisure de symétrie : théorie et applications". Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0536/document.
Testo completoThis work is focused on the decomposition of the magnetic exchange coupling ($J$) between magnetic centers in the broken-symmetry approach. The purpose of this method is to extract from unrestricted calculations the different contributions to the magnetic coupling: the direct exchange ($J_0$) between the magnetic orbitals, the kinetic exchange interaction ($\Delta J_{KE}$) allowing the delocalization of the magnetic orbitals and the core polarization ($\Delta J_{CP}$) of non-magnetic electrons. The first part of this thesis is centered on the theory of the decomposition method in the simplest case of a centro-symmetric system with two electrons in two magnetic centers. The physical meaning is explained in relation with methodological and theoretical tools used in this approach. The second part presents the implementation of the method in the Orca package and its application to non centro-symmetric systems. In particular, this application highlights the interest of a such automatic method in standard quantum package. The last part of this work is focused on the methodological developments carried out during these three years. An innovative method avoiding the spin contamination problem is presented to extract the spin polarization effects. Furthermore, a generalization of the decomposition of $J$ to more complicated systems with more than two electrons in two magnetic centers is discussed. Special attention was given to the explanation and physical meaning of broken symmetry approach in Hartree-Fock and Density Functional Theory
Cancès, Eric. "Simulation moléculaire et effets d'environnement - Une perspective mathématique et numérique". Phd thesis, Ecole des Ponts ParisTech, 1998. http://pastel.archives-ouvertes.fr/pastel-00000101.
Testo completoFarizon, Michel. "Agrégats d'hydrogène - Structure et interaction avec des cibles solides". Phd thesis, Université Claude Bernard - Lyon I, 1988. http://tel.archives-ouvertes.fr/tel-00795192.
Testo completoHasnaoui, Karim. "Transition de phase et frustration en physique nucléaire et astrophysique". Phd thesis, Université de Caen, 2008. http://tel.archives-ouvertes.fr/tel-00337606.
Testo completoBounthong, Bounseng. "Calculs microscopiques pour les noyaux exotiques de masse moyenne et lourde". Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE046/document.
Testo completoWe present an alternative approach to shell diagonalizations for microscopic description of nuclear structure. First we minimized the total system energy solving the Hartree-Fock equations within the shell model valence space. The results are compared with exact shell model diagonalization and an exact soluble SU(3) hamiltonian. Then, we developed procedures to obtain the same of type calculations with constrained conditions on the quadrupole degrees of freedom to obtain the full potential energy surfaces. The angular momentum restauration was obtained through projection method to generate rotionnal spectra of nuclei in both axial and triaxial cases. Finally the generate coordinate method was applied to mix several of these non-orthogonal Slater determinants. Among several applications we managed to describe deformed nuclei along the N=Z line around 80Zr or a new island of deformation at N=50. Finally, a first application in the superheavy region predicts a spherical gap for the Z=114, N=184 isotope
Bonneau, Ludovic. "Fission des noyaux lourds : étude microscopique des barrières de fission et du moment angulaire des fragments". Phd thesis, Université Sciences et Technologies - Bordeaux I, 2003. http://tel.archives-ouvertes.fr/tel-00005374.
Testo completoSayede, Adlane D. "Étude du comportement structural, électronique, catalytique et électrochimique des oxydes d'intercalation (V2O5, MoO3, WO3 et ReO3) par des méthodes du premier principe". Artois, 2003. http://www.theses.fr/2003ARTO0404.
Testo completoThis work concerns the determination of the structural, electronic, catalytic and electrochemical properties of a class of intercalation oxides (the pentoxyde of vanadium (V2O5), the trioxyde of molybdenum (MoO3), the trioxyde of tungsten (WO3) and the trioxyde of rhenium (ReO3)). In this goal we have used two first principle calculation methods : the Hartree-Fock (HF) method and the linear augmented planes wave (LAPW) method. These two methods allowed us to optimize the results relative to every studied property. The studied have an ionocovalent character on the bulk and surface level. Surface oxygens of V2O5 and MoO3 behave as species chemically distinct so offering an interesting catalytic activity. The adsorption of the hydrogens for example preferably takes place on molybdenyls oxygens on the surface (100) of alpha-MoO3. The effect of the insertion of the lithium on the surface of V2O5 was approached and shown that lithium ions yield its charge to the surface, which gives slightly modified electronic and structural properties. Intercalation of alkaline such lithium, sodium and potassium in ReO3 type oxides shows a modification of the structural, electronic and electrochemical properties of these oxides
Levitt, Antoine. "Etude théorique et numérique de modèles non linéaires en mécanique quantique". Phd thesis, Université Paris Dauphine - Paris IX, 2013. http://tel.archives-ouvertes.fr/tel-00881031.
Testo completoDucatez, Raphaël. "Analyse mathématique de divers systèmes de particules en milieu désordonné". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED013/document.
Testo completoThis thesis is devoted to the mathematical study of some systems of classical and quantum particles, in a disordered medium. It comprises four published or submitted works. In the first one we provide a new formula allowing to prove Anderson localisation in one space dimension and to characterise the decay at infinity of the eigenfunctions. The second contains one of the first proofs of localisation for infinitely many particles in interaction, in the Hartree-Fock approximation. The third work is dedicated to the Anderson model in a time-periodic perturbation. Under certain conditions on the oscillation frequency we prove the absence of diffusion. In the last work we show the decay of correlations for the one-dimensional Jellium model in an inhomogeneous background, using the Hilbert distance on cones and the Birkhoff-Hopf theorem
Liang, Haozhao. "Nuclear charge-exchange excitations in a self-consistent covariant approach". Paris 11, 2010. http://www.theses.fr/2010PA112178.
Testo completoNowadays, charge-exchange excitations in nuclei become one of the central topics in nuclear physics and astrophysics. Basically, a systematic pattern of the energy and collectivity of these excitations could provide direct information on the spin and isospin properties of the in-medium nuclear interaction, and the equation of state of asymmetric nuclear matter. Furthermore, a basic and critical quantity in nuclear structure, neutron skin thickness, can be determined indirectly by the sum rule of spin-dipole resonances (SOR) or the excitation energy spacing between the isobaric analog states (lAS) and Gamow-Teller resonances (GTR). More generally, charge-exchange excitations allow one to attack other kinds of problems outside the realm of nuclear structure, like the description of neutron star and supernova evolutions, the β-decay of nuclei which lie on the r-process path of stellar nucleosynthesis, and the neutrino-nucleus cross sections. They also play an essential role in extracting the value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vud via the nuclear 0+→ 0 + superallowed Fermi β decays. For all these reasons, it is important to develop the microscopic theories of charge-exchange excitations and it is the main motivation of the present work. Ln this work, a fully self-consistent charge-exchange relativistic random phase approximation (RPA) based on the relativistic Hartree-Fock (RHF) approach is established. Its self-consistency is verified by the so-called lAS check. This approach is then applied to investigate the nuclear spin-isospin resonances, isospin symmetry-breaking corrections for the superallowed β decays, and the charged-current neutrino-nucleus cross sections. For two important spin-isospin resonances, GTR and SOR, it is shown that a very satisfactory agreement with the experimental data can be obtained without any readjustment of the energy functional. Furthermore, the isoscalar mesons are found to play an essential role in spin-isospin resonances via the exchange terms, which leads to a profound effect in the nuclear isovector properties, e. G. , the density dependence of the symmetry energy in nuclear matter. Ln the investigation of the isospin symmetry-breaking corrections for the superallowed β decays, it is found that the corrections δc are sensitive to the proper treatments of the Coulomb mean field, but not so much to specific effective interactions. With these corrections δc, the nucleus-independent Ft values are obtained in combination with the experimental ft values in the most recent survey and the improved radiative corrections. The values of Cabibbo-Kobayashi-Maskawa matrix element IVudI thus obtained weil agree with those obtained in neutron decay, pion decay, and nuclear mirror transitions, while the sum of squared top-row elements somehow deviates from the unitarity condition. Expressing the weak lepton-hadron interaction in the standard current-current form, the relevant transitions from the nuclear ground state to the excited states are calculated with RHF+RPA approach. Ln this way, the semileptonic weak interaction processes, e. G. , neutrino reactions, charged- lepton capture, β-decays, can be investigated microscopically and self-consistently. First illustrative calculations of the inclusive neutrino-nucleus cross section are performed for the 16 O(Ve ,e-)16 F reaction, and a good agreement with the previous theoretical studies is obtained. The main effort is dedicated to discussing the substantial influence of different recipes for the axial vector coupling strength and the theoretical low-Iying excited states of the daughter nucleus
Pichon-Pesme, Virginie. "Étude de l'effet anomérique par analyse de la densité électronique". Nancy 1, 1986. http://www.theses.fr/1986NAN10088.
Testo completoOlivieri, Lilian. "Recherche et caractérisation par dynamique moléculaire d'états intermédiaires pour la complexation entre la protéine FKBP12 et des ligands de haute affinité". Thesis, La Réunion, 2012. http://www.theses.fr/2012LARE0011/document.
Testo completoFKBP12 is an ubiquitous, mostly cytosolic, protein found at the crossroads of several signaling pathways. Its natural abundance in the nervous tissues can be related to its implication in neurodegenerative diseases like Alzheimer's and Parkinson's as well as in peripheral neuropathies and diabetes or in injuries of the spinal cords. Several studies have demonstrated that exogenous molecules (ligands) that can bind to FKBP12 allow the regeneration of many damaged neuron connections. However, there is no clear relationship between the structure of a ligand and its ability to bind to FKBP12. Our study aims at rationalizing the relationship between the structure of a ligand and its affinity to FKBP12. Two model complexes, formed between FKBP12 and each of the two high-affinity ligands 8 and 308, were studied. These two ligands are structurally different. We used molecular dynamics simulations to characterize the intermediate state that is transiently formed during the binding process between the protein and its ligand. In this state, the analysis of the nascent interactions allowed (i) to unravel the role played by the various ligand moieties in the recognition process with FKBP12 and (ii) to rationalize the affinities of related ligands
Trebbia, Jean-Baptiste. "Etude de gaz quantiques dégénérés quasi-unidimensionnels confinés par une micro-structure". Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00186656.
Testo completoMourad, Nahia. "Fondements mathématiques et numériques de la méthode des pseudo-potentiels". Thesis, Paris Est, 2015. http://www.theses.fr/2015PESC1024/document.
Testo completoThe contributions of this thesis consist of three main results. The first result is concerned with analytic perturbation theory for Kohn-Sham type models. We prove, under some technical conditions, the existence, uniqueness and analyticity of the perturbed reduced Hartree-Fock ground state density matrix for regular perturbations arising from an external potential. Our analysis encompasses the case when the Fermi level of the unperturbed ground state is a degenerate eigenvalue of the mean-field operator and the frontier orbitals are partially occupied. The second result is concerned with the mathematical construction of pseudo potentials for Kohn-Sham models. We define a set of admissible semi local norm-conserving pseudo potentials of given local Sobolev regularity and prove that this set is non-empty and closed for an appropriate topology. This allows us to propose a new way to construct pseudo potentials, which consists in optimizing on the latter set some criterion taking into account both smoothness and transferability requirements. The third result is a numerical study of the reduced Hartree-Fock model of atoms. We propose a discretization method and an algorithm to solve numerically the Kohn-Sham equations for an atom subjected to a cylindrically-symmetric external potential. We report the computed occupied energy levels and the occupation numbers for all the atoms of the four first rows of the periodic table and consider the case of an atom subjected to a uniform electric-field
Dianzinga, Mamy Rivo. "N-representable density matrix perturbation theory". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0285/document.
Testo completoWhereas standard approaches for solving the electronic structures present acomputer effort scaling with the cube of the number of atoms, solutions to overcomethis cubic wall are now well established for the ground state properties, and allow toreach the asymptotic linear-scaling, O(N). These solutions are based on thenearsightedness of the density matrix and the development of a theoreticalframework allowing bypassing the standard eigenvalue problem to directly solve thedensity matrix. The density matrix purification theory constitutes a branch of such atheoretical framework. Similarly to earlier developments of O(N) methodology appliedto the ground state, the perturbation theory necessary for the calculation of responsefunctions must be revised to circumvent the use of expensive routines, such asmatrix diagonalization and sum-over-states. The key point is to develop a robustmethod based only on the search of the perturbed density matrix, for which, ideally,only sparse matrix multiplications are required. In the first part of this work, we derivea canonical purification, which respects the N-representability conditions of the oneparticledensity matrix for both unperturbed and perturbed electronic structurecalculations. We show that this purification polynomial is self-consistent andconverges systematically to the right solution. As a second part of this work, we applythe method to the computation of static non-linear response tensors as measured inoptical spectroscopy. Beyond the possibility of achieving linear-scaling calculations,we demonstrate that the N-representability conditions are a prerequisite to ensurereliability of the results
Ducoin, C. "Rôle de l'isospin dans la transition de phase liquide-gaz de la matière nucléaire". Phd thesis, Université de Caen, 2006. http://tel.archives-ouvertes.fr/tel-00110371.
Testo completoLa transition liquide-gaz nucléaire est associée au phénomène de multi-fragmentation observé dans les collisions d'ions lourds, ainsi qu'à la physique des étoiles compactes : les systèmes concernés sont riches en neutrons, donc affectés par le degré de liberté d'isospin.
Le travail présenté ici est une étude théorique des effets d'isospin apparaissant dans la transition liquide-gaz de la matière nucléaire asymétrique. Une approche de champ moyen est employée, avec une interaction nucléaire effective de type Skyrme. Nous démontrons la présence d'une transition du premier ordre pour la matière asymétrique, et étudions le phénomène de distillation d'isospin qui l'accompagne. Le cas d'une séparation de phase à l'équilibre thermodynamique est comparé à celui d'une décomposition spinodale. Les effets de taille finie sont abordés, ainsi que l'influence du gaz d'électrons présent dans le contexte astrophysique.
Mougeot, Maxime. "Nuclear Collectivity Studied through High Precision Mass Measurements of Neutron-rich Argon and Chromium Isotopes". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS455/document.
Testo completoDue to their inherent relationship with the binding energy, nuclear masses are the fingerprint of all the interactions taking place within the nucleus. As such, precise and accurate mass values are an essential ingredient to the comprehensive understanding of nuclear phenomena in exotic regions of the chart of nuclides. In this thesis, two key regions exhibiting dramatic structural evolution are investigated by means of high precision mass measurements performed with the online mass spectrometer ISOLTRAP at ISOLDE/CERN. Numerous spectroscopy results indicate that the chromium isotopic chain exhibits the most dramatic structural changes within the region situated south of 68Ni. This thesis reports on the first high-precision mass measurements of the neutron-rich 58-63Cr isotopes using the well established Penning trap mass spectrometry technique as well as the MRToF-MS technique pioneered at ISOLTRAP in recent years. The obtained mass values are up to 300 times more precise than the ones currently available in the literature. At odds with previous results, the new mass values exclude a sudden onset of ground-state collectivity rather favouring a smooth transition towards deformation approaching N=40. The question of the persistence of the N=28 shell closure in the Argon chain is also studied in this PhD work through the measurement of the neutron-rich 46-48Ar isotopes. The results of improved precision confirm the presence of a strong N=28 shell closure in the Argon chain. For both datasets, the detailed data analysis procedure will be presented. The implication of the obtained mass values for nuclear structure will be discussed through a phenomenological discussion of the binding energy trend. The results will also be discussed in the light of state of the art nuclear models including results from the promising valence-space formulation of the ab-initio IM-SRG formalism
Xayavong, Latsamy. "Calculs théoriques de corrections nucléaires aux taux de transitions β super-permises pour les tests du Modèle Standard". Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0406/document.
Testo completoThe conservation of the weak vector current, known as CVC is one of the fundamentalhypothesis of the Standard Model of the electroweak interaction. Nevertheless,the physics background of this hypothesis is nothing more than an analogyto the electromagnetic interaction's theory and the question of its validity remainsopen. The CVC is veri_able in the superallowed Fermi β-decays, 0+ → 0+, T = 1since it predicts that the Ft (≡ corrected ft) value of such low-energy processesmust be nucleus independent. Once the unique Ft value is found, one can immediatelydeduce the vector coupling constant GV , linked to │Vud, the norm of themost important element of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixingmatrix. This matrix element plays a crucial role in the test of the unitarity of theCKM matrix, another fundamental hypothesis of the Standard Model.Currently, 14 superallowed transitions ranging from 10C to 74Rb are known experimentally with the precision 0.1% or better. This results in a fact that this studyis now limited by the theoretical corrections, due to the radiative and the isospin symmetry-breaking effects. The aim of this thesis is to re-examine the correction due to mismatch between proton and neutron radial wave functions (ᵟRO) within the framework of shell model. We adopted the method recently developed by Towner and Hardy [1]. This method combines realistic radial wave functions with spectroscopic informations obtained from a large-scale shell-model calculation, thus allowing us to go beyond traditional shell-model approaches. In this work, we considered 13 superallowed transitions, including : 22Mg, 26Al, 26Si, 30S, 34Cl, 34Ar, 38K, 38Ca, 46V, 50Mn, 54Co, 62Ga et 66As. The radial wave functions were determined with a realistic single-particle potential, such as the phenomenological Woods-Saxon (WS) potential or the self-consistent Hartree-Fock (HF) mean field derived from an effective Skyrme force. We selected various parametrizations (2 parametrizations for WS and 3 Skyrme forces for HF) that seem to us to be appropriate for our purposes. First, we performed the calculations with a simple method, without taking into account the intermediate states. The result indicates that ᵟRO obtained from WS potential is strongly parametrization dependent. In order to clarify this effect, we studied profoundly the sensitivity to potential parameters, paying particular attention to the isovector and the Coulomb terms.This study provided evidence that such a dependence is entirely dominated by the isovector part of the potential. However, using our proposed adjustment procedure, this problem appears to be well under control. We also examined the surface terms adopted in the work of Towner and Hardy [1], the result showed that one of these terms (the term Vh(r)) is not compatible with our adjustment procedure. (...)
Koh, Meng hock. "Fission-barriers and energy spectra of odd-mass actinide nuclei in self-consistent mean-field calculations". Thesis, Bordeaux, 2015. http://www.theses.fr/2015BORD0208/document.
Testo completoWhile there have been numerous microscopic calculations on fission barriers of even-even compoundnuclei, there are however, relatively few such work dedicated to odd-mass nuclei. This is dueto the complications posed by the breaking of the time-reversal symmetry at the mean-field leveldue to the presence of an unpaired nucleon. In order to circumvent this difficulty, previous fission barriercalculations of odd-mass nuclei have been performed by neglecting the effect of time-reversalsymmetry breaking. This work aims to improve on the description of fission barriers as well asthe spectroscopic properties of ground and fission-isomeric state, of some odd-mass actinide nucleiby taking the effect of time-reversal symmetry breaking into account. This has been perfomedwithin a Skyrme-Hartree-Fock-plus-BCS framework with blocking, where the BCS formalism hasbeen adapted to accomodate this symmetry breaking. The Skyrme nucleon-nucleon effective forcehas been used with various sets of parameters (SIII, SkM*, SLy5*). The residual pairing interactionhas been approximated by seniority forces whose neutron and proton parameters have beenfitted to reproduce the odd-even mass differences of some actinide nuclei. The low-lying rotationalband-head energies evaluated within the Bohr-Mottelson unified model have been determined forfour well-deformed odd-nuclei (235U, 239Pu, 237Np, 241Am) yielding a good qualitative agreementto the data for odd-neutron nuclei. The agreement was significantly less good for the odd-protonnuclei, possibly due to the use of the Slater approximation for the exchange Coulomb interaction.The deformation energies of two odd-neutron nuclei (235U and 239Pu) have been calculated forsome single-particle configurations up to a point beyond the outer fission-barrier. Axial symmetrynuclear shape has been assumed while a breaking of the left-right (or intrinsic parity) symmetryhas been allowed around the outer fission-barrier. The fission-barrier heights of such odd-neutronnuclei depend significantly on the particle configurations. A special attention has been paid tothe very important rotational correction to deformation energies. In particular, the correction ofthe moment of inertia calculated from the usual Belyaev expression was considered. Overall, aqualitative agreement with available data on fission-barrier heights for the considered odd-neutronnuclei and their even neighbours has been obtained
Sala, Matthieu. "Quantum dynamics and laser control for photochemistry". Thesis, Dijon, 2015. http://www.theses.fr/2015DIJOS039.
Testo completoThe central subject of this thesis is the theoretical description of ultrafast dynamical processes in molecular systems of chemical interest and of their control by laser pulses. We first use electronic structure calculations to study the photochemistry of aniline. A umber of previously unknown features of the potential energy surfaces of the low-lying elec-tronic states are reported, and analyzed in relation with the experimental results available. We use quantum dynamics simulations, based on a model Hamiltonian including the four lowest excited electronic states and sixteen vibrational modes, to investigate the photochem-istry of pyrazine. We show that the dark Au(nπ∗) state plays an important role in the ultrafast dynamics of the molecule after photoexcitation. The laser control of the excited state dynamics of pyrazine is studied using a simplified two-state four-mode model Hamiltonian. We propose a control mechanism to enhance the lifetime of the bright B2u(ππ∗) state using the Stark effect induced by a strong non-resonant laser pulse. We finally focus on the laser control of the tunneling dynamics of the NHD2 molecule, using accurate full-dimensional potential energy and dipole moment surfaces. We use simple effective Hamiltonians to explore the effect of the laser parameters on the dynamics and design suitable laser fields to achieve the control. These laser fields are then used in MCTDH quantum dynamics simulations. Both enhancement and suppression of tunneling are achieved in our model