Dissertations / Theses on the topic 'Analyse de la densité électronique'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Analyse de la densité électronique.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
Pichon-Pesme, Virginie. "Étude de l'effet anomérique par analyse de la densité électronique." Nancy 1, 1986. http://www.theses.fr/1986NAN10088.
Abellaoui, Lahcen. "Conception d'un analyseur numérique de densité spectrale de bruit de fond électronique." Montpellier 2, 1989. http://www.theses.fr/1989MON20235.
Bec, Emmanuel. "Prédiction et contrôle de la densité électronique en vue de l'analyse conformationnelle de molécules complexes." Université de Marne-la-Vallée, 1998. http://www.theses.fr/1998MARN0027.
Hanna, Pierre. "Modélisation statistique de sons bruités : étude de la densité spectrale, analyse, transformation musicale et synthèse." Bordeaux 1, 2003. http://www.theses.fr/2003BOR12756.
Lontsi, Fomena Mireille. "Etude théorique de la diffusion de l'oxygène dans des oxydes diélectriques$bRessource électronique." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2008. http://tel.archives-ouvertes.fr/tel-00402631.
Aubert, Flavien. "Étude conjointe par calculs ab-initio et analyse de la densité électronique du composé moléculaire (EDO-TTF)₂-PF₆ présentant une transition métal-isolant." Rennes 1, 2008. http://www.theses.fr/2008REN1S146.
During this work, we have investigated, using DFT calculation and topological analysis of the electron density, the metal to insulator phase transition occuring in the organic compound (EDO-TTF)2PF6. This phase transition takes place at 278K but can also be photo-induced on pico-second time scale. It also exhibits many different aspects of phase transition : Peierls like instability, exotic 0 +1 +1 0 charge ordering of EDO-TTF tetramers and orientational ordering of PF6 ions. Using high and low temperature band structure as well as bond critical points analysis we could fit a tight-binding model to ab-initio calculations from which we have been able to find and characterize the charge density wave and propose a transition mechanism governed by coulombic interactions
Tristant, Damien. "Analyse des améliorations des propriétés électroniques des matériaux carbonés par interaction d'espèces chimiques : Approche numérique combinée à la spectroscopie Raman." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0005/document.
To analyze the improvements in electronic properties of carbon-based materials, an approach based on the density functional theory supported by Raman spectroscopy was used. The heart of this work is the study of doping in order to open up new paths for the design of innovative materials from nanodevices. These new structures are fibers whose the main component is a carbon nanotube or nanocarbon loaded polymers with molecules, optimizing electrical conduction. A brief introduction is presented on non-covalent species, leading to the best results reported in the literature, namely potassium, iodine and super acids. The graphite intercalation compounds by potassium atoms are analyzed first. The large charge transfer of the alkali directly influences the optical properties of graphene, resulting in a unique Raman signature with a shape change when the excitation energy is twice the shift of the Fermi level due to doping. Then, an exhaustive theoretical study of iodine doping is performed on a monolayer of graphene. Analysis of thermodynamic properties shows that a gradual increase in the recovery rate of the molecules, initially generates a phase transition of iodine adsorption mode, and ends with the formation of polyiodide complexes. These complexes, via a strong electron transfer, lead to the increase of the density of states at the Fermi level. This study is extended to carbon nanotubes, where a very large charge transfer is obtained after interacting either with chlorosulfonic acid molecules by redox reaction, or with iodine molecules. When there is a flow of a large electric current in these fibers, the Joule effect produces a desorption of dopants and reduces the electrical conductivity. This phenomenon is explained by the available number of conduction channels deducted from combined Raman signatures and electronic transport calculations. The local and average temperatures are extracted from Raman and transport data respectively. This work constitutes a coherent set of results as a basis for improving the transport properties
Saverot-Dauvergne, Agnès. "Modifications des lipoprotèines de haute densité (HDL) d'origine humaine et de leurs sous-classes (HDL2, HDL3) par des liposomes de phosphatidylcholines et de sphingomyélines : analyse biochimique et étude structurale par résonance paramagnétique électronique (RPE)." Paris 5, 1990. http://www.theses.fr/1990PA05P619.
Amriou, Tayeb. "Etude ab-initio de la strucutre électronique des composés lamellaires intercalés detype AMX2. Application aux batteries rechargeables." Artois, 2003. http://www.theses.fr/2003ARTO0405.
This work describes a general study of the layered compounds AMX2 (A = Li, Na ; M = Transition Metals; X = O, S, Se) usually used as positive electrode in the rechargeable batteries. First principal calculations are used to investigate the structural, electronic and electrochemical properties of theses compounds. The open circuit voltage variation is correlated to the nature of the alkali, the transition metal and the chalcogene. The results are interpreted with the charge transfer phenomena. It has been shown that the behaviour with the lithium intercalation is different from sodium intercalation. So, the understanding of the charge transfer is the key criteria to obtain a high potential
Sayede, 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.
This 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
Granier, Agnès. "Étude des décharges créées par onde de surface à moyenne et haute pression : application à l'analyse chimique." Paris 11, 1986. http://www.theses.fr/1986PA112177.
This report deals with the study of microwave discharges produced in argon gas by surface waves in the 20-760 Torr pressure range. Application to chemical analysis by emission optical spectroscopy is also investigated. First of all we study the propagation of a surface wave in bounded plasma in which the effective collision frequency for momentum transfer ν is higher than the excitation one. The axial electron density profile is determined from two diagnostic techniques, i. E. , phase variations of the wave field and Stark broadening of Hβ line. Then we deduce the discharge characteristics ν, Θ (maintaining power of an electron-ion pair) and Eeff (effective electric field for discharge sustaining) from the electron density profile. Then an energy balance of the discharge is developed. It explains the change of operating conditions in the 20-50 Torr range. At low pressure the discharge is governed by ambipolar diffusion whereas at high pressure, the electrons are mainly lost by volume recombination of Ar2+. Finally, we report on chemical analysis experiment of gases (optimum sensibility in found near 100 Torr) and of metallic solutions sprayed by a graphite oven. Performances of such a design and ICP plasma torches are compared
Etude de décharges microondes d'argon créées par onde de surface à moyenne et haute pressions (20-760 Torr) dans des tubes capillaires ainsi que leur utilisation pour l'analyse chimique par spectrométrie d'émission
Lontsi, Fomena Mireille. "Etude théorique de la diffusion de l’oxygène dans des oxydes diélectriques." Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR13703/document.
The miniaturization of CMOS (Complementary Metal Oxide Semiconductor) components requires the use of high dielectric permittivity materials as gate oxide. LaAlO3 and SrTiO3 are among the best candidates, but the oxygen diffusion in these materials leads to the degradation of both the electrical properties and the interface with silicon. In this context, the aim of this theoretical work is to study the factors governing the oxygen ion diffusion at the chemical bonding scale. This approach is based on Density Functional Theory (DFT), coupled with electron density analysis methods, and the pioneering development of energy density cards. The regions of the electron density contributing to the diffusion barrier have been identified allowing new routes of optimization of these materials across the chemical bonding
Brezgunova, Mariya. "Analyse de la densité de charge et des propriétés topologiques des interactions intermoléculaires faibles - liaisons halogène et chalcogène - et leur comparaison avec des liaisons hydrogène." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0012/document.
Understanding and control of intermolecular interactions play a crucial role in molecular recognition, crystal engineering, and biological systems. Three very frequent weak contacts linking the molecules in organic solids are halogen, chalcogen, and weak hydrogen bondings. In this thesis, we perform experimental and theoretical charge density rho(r) studies based on the QTAIM methodology for analyzing halogen and chalcogen bonding, and for comparing them with weak hydrogen bonding, as derived from the high-resolution single crystal X-ray diffraction multipole-refined electron density and from density functional theory (DFT) calculations. Defining the nature of these weak interactions as electrophilic-nucleophilic, we particularly focus on their strength and directionality. Based on the topology of L(r) = ¬rho inverted delta2 rho(r), a proposed electrostatic descriptor (delta(L/rho)) permitted us to evaluate quantitatively the electrostatic intensity between charge concentration (CC) and charge depletion (CD) regions belonging to the valence shell of the interacting atoms. The interaction energy (Eint) was described from the topological properties of rho(r). The attention has been also paid to the formation of recurrent structural fragments, called synthons. By the developed approach, it is proved that the synthon arrangement can be created not only by groups of atoms, but also by sets of CC and CD sites similarly involved in the contact formation
Sciamma, Ella Marion. "Développement d'un outil de diagnostique par spectroscopie des plasmas utilisant des modèles collisionel-radiatifs et son application à différentes décharges plasma pour la détermination de la température électronique et de la densité des neutres." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/118/.
A spectroscopic diagnostic tool has been developed to determine the electron temperature and the neutral density in helium, hydrogen and argon plasmas from absolutely calibrated spectroscopic measurements. For each gas, a method of analysis which uses models specific to each species present in the plasma has been defined. The experimental electron density is used an input parameter to the models, and the obsolutely calibrated spectroscopic data are processed beforehand to obtain the populations of the upper excited levels corresponding to the observed spectral lines. Fro helium plasmas, the electron temperature is inferred from the experimental helium ion excited level p = 4 population using a corona model, and the neutral density is determined from the experimental helium neutral excited level populations using a collisional-radiative model for helium neutrals. For hydrogen plasmas, combinations of the electron temperature and the neutral density are determined from the experimental hydrogen neutral excited level populations using a collisional-radiative model for hydrogen atoms. For argon plasmas, the electron temperature is inferred from the experimental argon ion excited level population using a collisional-radiative model for argon ions, and then the neutral density is determined from experimental argon neutral excited level populations using a collisional-radiative model for argon neutrals. .
Frayret, Christine. "Application de la Théorie de la Fonctionnelle de la Densité à la modélisation de la diffusion de l'ion oxygène dans des électrolytes solides modèles et des conducteurs mixtes." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2004. http://tel.archives-ouvertes.fr/tel-00010824.
Voufack, Ariste Bolivard. "Modélisation multi-technique de la densité électronique." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0168/document.
X-ray and neutron diffraction methods can be combined to determine simultaneously electron charge and spin densities in crystals based on spin resolved electron density model developed at CRM2. This method enables to carry out the study of interaction paths leading to the observed ferromagnetic order. First applications of this model were to coordination complexes, where the unpaired electron is mainly located on the transition metal, then generalized to explore organic radicals and to inorganic materials. In radical Nit(SMe)Ph, the modeling of the experimental charge and spin densities showed localization of spin density on O-N-C-N-O group (nitronyl -nitroxyde function), in agreement with previous works. It is also evidenced the involvement of the hydrogen bonds in the magnetic interactions leading to the ferromagnetic transition at very low temperature (0.6K). This study revealed dissymmetrical spin population of the two N-O groups that only CASSCF-type calculations can reproduce in amplitude (not DFT). This dissymmetry originates from both molecular and crystal effects. In radical p-O2NC6F4CNSSN belonging to the family of dithiadiazolyl, the joint refinement showed that the majority of the spin is distributed on -CNSSN group in agreement with the previous works. From topological properties of the charge density, halogen, chalcogen and π interactions have been highlighted. The most important magnetic interactions are observed through the network formed by contacts S ... N2 between neighboring molecules leading to the ferromagnetic order below 1.23K. Concerning the inorganic material, YTiO3, the charge densities in both paramagnetic and ferromagnetic phases and spin density were modelled. The results show that the most populated d orbitals of Ti atom are dxz and dyz. The orbital ordering evidenced in this material is observed at 100 and 20 K due to the orthorhombic distorsion. The wave function of the unpaired electron is a linear combination of these particularly populated t2g orbitals
Voufack, Ariste Bolivard. "Modélisation multi-technique de la densité électronique." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0168.
X-ray and neutron diffraction methods can be combined to determine simultaneously electron charge and spin densities in crystals based on spin resolved electron density model developed at CRM2. This method enables to carry out the study of interaction paths leading to the observed ferromagnetic order. First applications of this model were to coordination complexes, where the unpaired electron is mainly located on the transition metal, then generalized to explore organic radicals and to inorganic materials. In radical Nit(SMe)Ph, the modeling of the experimental charge and spin densities showed localization of spin density on O-N-C-N-O group (nitronyl -nitroxyde function), in agreement with previous works. It is also evidenced the involvement of the hydrogen bonds in the magnetic interactions leading to the ferromagnetic transition at very low temperature (0.6K). This study revealed dissymmetrical spin population of the two N-O groups that only CASSCF-type calculations can reproduce in amplitude (not DFT). This dissymmetry originates from both molecular and crystal effects. In radical p-O2NC6F4CNSSN belonging to the family of dithiadiazolyl, the joint refinement showed that the majority of the spin is distributed on -CNSSN group in agreement with the previous works. From topological properties of the charge density, halogen, chalcogen and π interactions have been highlighted. The most important magnetic interactions are observed through the network formed by contacts S ... N2 between neighboring molecules leading to the ferromagnetic order below 1.23K. Concerning the inorganic material, YTiO3, the charge densities in both paramagnetic and ferromagnetic phases and spin density were modelled. The results show that the most populated d orbitals of Ti atom are dxz and dyz. The orbital ordering evidenced in this material is observed at 100 and 20 K due to the orthorhombic distorsion. The wave function of the unpaired electron is a linear combination of these particularly populated t2g orbitals
Hirrien, Bertrand. "Rugosité de surface et d'interface : méthodes de microscopie de force atomique et réflectivité de rayons-X rasants appliqués aux composants de la micro-électronique et de l'optronique." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0179.
Lachekar, Hassane. "Transfert des paramètres de densité électronique et applications." Nancy 1, 1997. http://www.theses.fr/1997NAN10209.
Cortona, Pietro. "Théories des fonctionnelles de la densité : nouvelles approximations et applications." Paris 11, 1987. http://www.theses.fr/1987PA112286.
We extended the applicability range of the density-functional theory to the case of relativistic spin-polarized systems. The difficulty of this case is due to the fact that the spin polarisation and the spin orbit effect together break the degeneracy of the system; so neither the total angular momentum j, nor its orbital part L are good quantum numbers of the system. This last point implies that the only way of writing the wave functions is by an infinite series of Dirac orbitals. However, this difficulty can be circumvented: we indicated a method to obtain an explic1te solution in the atomic case. By this method, which can be extended to treat solids, we studied the magnetic properties of the trivalent rare earth ions. We have also proposed a new approximation to the exchange part of the exchange-correlation energy functional. Our approximation treats exactly the self-interaction terms and uses, in a more consistent way than other analogous methods, the homogeneous gas theory in order to obtain an approximate expression of the inter-electron exchange energy. We tested our method by extensive calculations of the electronic properties of many atomic systems: the results show a systematic Improvement both of the local-density and the other self -interaction-corrected results. Next, we extended our method in order to treat relativistic systems. This can be immediatly obtained alter deriving the relativistic inter-electronic exchange energy expression for the homogeneous gas. Using the version of the theory, we showed that the local-density approximation is not appropriate to study solids containing heavy elements. Finally, we studied the charge distributions of solids of alkali halides. We were mainly interested into the ionic deformations due to the crystal field: so we determined the structure factors of these solids by a band calculation in the local-density approximation and we compared these results both with the experimental and with theoretical free-ions results. Ln this wag, we were able to show that the anions in the solids contract; on the other hand our calculations showed that the simple local-density approximation is sufficient to study charge density in ionic solids
Zaghzi, Mohamed. "Elaboration d'un rhizomètre pour l'étude de la densité racinaire." Mulhouse, 1987. http://www.theses.fr/1987MULH0038.
Zigah, Kwami Dodzi. "Analyse de surfaces par imagerie électronique." Rennes 1, 2009. http://www.theses.fr/2009REN1S048.
With the progressive decrease in the size of electronic devices, scientists were obliged to develop tools capable of analyzing surface reactivity on microscopic level. This marked the birth of SECM (Scanning ElectroChemical Microscopy). This technique, derived from scan probe microscopy (STM, AFM) makes it possible the study a local area based on ultramicroelectrodes properties (UME). The UME and the surface to be analyzed are placed in an electrolyte solution containing a redox mediator. The SECM provides a real "brush" chemical that will probe the surface. The first part of this work focused on the study of conducting and insulating surfaces, composed of carbon and silicon respectively, which were functionalized by a stable redox molecule (ferrocene), at an oxidized and reduced state. We then studied more complex systems. We used the SECM method to fellow the biocatalytic formation on a conducting and an insulated surface. In the last part of this thesis, we studied the electrode/ionic liquid interfaces. Ionic liquids are salt liquids at room temperature, mostly used in chemistry as a substitute for conventional solvents. With a theoretical model, we used SECM in transient conditions, to determine the diffusion coefficients of organic molecules in this type of solvent
Tazi, Mouhsine. "Détermination de champs de forces de la porphine et des métalloporphines à l'aide de la théorie de la fonctionnelle de densité et leur validation par le calcul des intensités Raman de résonance." Lille 1, 2000. http://www.theses.fr/2000LIL10135.
Wieduwilt, Erna K. "Quantum mechanics-based methods for the refinement of crystal structures and the analysis of non-covalent interactions." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0167.
In the work presented in this thesis, extremely localized molecular orbitals (ELMOs) were used as electronic LEGO building blocks to accomplish mainly two goals: (i) obtaining more accurate X-ray crystal structures for small and large systems, and (ii) analyzing non-covalent interactions in biomolecules. In fact, ELMOs are molecular orbitals that are strictly localized on small molecular fragments. Due to this strict localization, they may be computed on small molecules, stored in databases and then transferred to larger systems to reconstruct their wavefunctions and electron densities. To this end, we exploited the ELMO libraries, which contain the ELMOs for all the elementary fragments (atoms, bonds and functional groups) of the twenty natural amino acids. In situations where a higher accuracy was needed, we used the QM/ELMO embedding technique, in which the crucial part of the system under exam is treated at a higher quantum mechanical level, while the rest is described using frozen ELMOs. Concerning the first of the goals mentioned above, it is important to note that standard crystallographic refinements are based on the so-called independent atom model (IAM), which approximates the electron density as a sum of spherically averaged atomic densities. However, the element-hydrogen bond lengths resulting from IAM refinements are systematically too short. A method that solves this problem is the Hirshfeld atom refinement (HAR), a technique based on directly computing the electron density for the molecule under exam using quantum mechanical calculations. For small molecules, HAR has been proven to give element-hydrogen bond lengths that are in very good agreement with neutron reference values. However, for large systems, the applicability of the traditional HAR method is limited because the underlying fully QM calculations become computationally too expensive. Therefore, in the work presented in this thesis, the ELMO libraries and the QM/ELMO techniques have been coupled with the HAR method to refine large systems and also to obtain more accurate structures of small molecules. Furthermore, the necessity of using post-HF methods for HAR has been also evaluated. Concerning the second goal addressed in this dissertation, a similar problem as the one met in X-ray crystallography also arises in the analysis of non-covalent interactions. In fact, also the non-covalent interaction (NCI) and independent gradient model (IGM) techniques, which are commonly applied in analyses of non-covalent interactions, crucially depend on the computation of the electron density. Therefore, to analyze non-covalent interactions in large systems, both techniques had to resort to promolecular electron densities, which are the same densities used in the IAM. However, also in the cases of NCI and IGM analyses, these densities provide biased results. To overcome this drawback, we have coupled both methods with the ELMO libraries, giving rise to the NCI-ELMO and IGM-ELMO techniques, which were then applied to identify, classify and approximately quantify non-covalent interactions in polypeptides and proteins
Syamala, Vishnu Vijayakumar. "Molecular organization in solid-state using sigma-hole interactions : Exploring the effect of crystalline environment." Electronic Thesis or Diss., Université de Lorraine, 2022. https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2022_0214_VIJAYAKUMAR_SYAMALA.pdf.
Understanding the fundamentals of the formation and stabilization of non-covalent interactions is of paramount importance in the field of crystal engineering. In this direction, this thesis reports the crystallographic investigation of a sub-class of non-covalent interactions known as sigma-hole interactions. sigma-hole interactions are defined as those involving electrophilic sites (also called sigma-holes) associated to a covalently bonded atom belonging to either p-block (groups 13-18) or d-block (groups 8,11 and 12) of the periodic table, and nucleophilic sites coming from either the same or a different molecule. Depending upon the group of the atom on which the sigma-hole is present, the interaction can be further classified into various sub-classes. Out of these, we have focused on the cases of halogen bond (HaB) and chalcogen bond (ChB) interactions. As compared to the well-established case of hydrogen bonds (HB), the rationale behind the formation and stabilization of HaB and ChB are still less explored. This thesis is aimed exactly in such a direction, to provide a deeper insight into the characteristics of HaB and ChB interactions, mainly by understanding how the electron density is distributed among the interacting pair of atoms and how it eventually influences the molecular organization in solid-state. Two main stream topics of crystallography are covered during the course of this thesis: (i) high-pressure X-ray diffraction studies and (ii) charge density analysis. Structural and electronic investigations are carried out based on the data derived from single-crystal X-ray diffraction (SCXRD) experiments performed either at ambient or extreme conditions. The so-obtained crystal structures were used to derive the electron density distribution in the periodic phases. The electron distributions of the molecular systems extracted from their crystalline environments were used to calculate the electrostatic potential in molecular surfaces and to carry out the topological analyses of the electron density and its laplacian function within the framework of the Quantum Theory of Atoms in Molecules (QTAIM) methodology. The effect of crystalline environments in tuning the properties of sigma-hole interactions is also explored in detail. The information gathered from such analyses is not only helpful to better understand the molecules in hands, but also to design new molecular patterns with the aim to control the structure-properties relationship in molecular crystals
Souhassou, Mohamed. "Densité d'électrons dans les composés peptidiques par méthode X-X et calcul théorique : LA (N) acétyl-L-tryptophane-méthylamide et la (N)-acétyl-alpha-béta -dehydrophenylalanine-methylamide, influence de La alpha -beta -déhydrogénation et étude critique des modèles multipolaires." Nancy 1, 1988. http://www.theses.fr/1988NAN10418.
Gicquel, Mickael. "Carbo-oxocarbones, analyse de la délocalisation électronique." Toulouse 3, 2007. http://thesesups.ups-tlse.fr/141/.
The effect of the carbo-merization on the global structure and stability of oxocarbons (CnOn) has been studied theoretically. In contrast to their geometry, the relative energy of carbo-[N]oxocarbons C3NON (N = 1 to 5) and their polycyclic isomers is highly sensitive to the calculation level. On the basis of calculation at the B3PW91/6-311+G* level, the static and dynamic electron delocalization has been investigated, by ELF and ring current analysis, respectively. Carbo-[N]oxocarbons are non-aromatic (N = 3). The central ring of their polycyclic isomer is aromatic (respectively anti-aromatic) for odd N (respectively even N), while the aromatic character of the externals three-membered rings is comparable to the one of cyclopropenone. The stability of the ring carbo-mers has been established on the basis of their endothermic decomposition in C3O. Related aspects have also been considered: orbital analysis, kinetic stability, resonance weighting, homoaromatic component, multiconfigurational character, singlet-triplet gap, organometallic complexe, oligocarbonylethynylene acyclic references
Laamyem, Abdelghani. "Densité électronique du composé : [mu]-Diter-Butylacétylène hexacarbonyle di-Fer : étude expérimentale et théorique." Lille 1, 1988. http://www.theses.fr/1988LIL10039.
Lamare, Lucien. "Calculs de structure électronique et de courant tunnel relatifs à une jonction STM métallique." Dijon, 1997. http://www.theses.fr/1997DIJOS022.
Fluteaux, Christophe. "Contribution à l'étude de la densité électronique des composés ioniques par diffusion inélastique des rayons X." Châtenay-Malabry, Ecole centrale de Paris, 1999. http://www.theses.fr/1999ECAP0635.
Agostini, Eric. "Mesure de température et de densité électronique par diffusion Thomson sur le tokamak TORE SUPRA." Aix-Marseille 3, 1991. http://www.theses.fr/1991AIX30057.
Vachey, Eric. "Analyse et exploitation du signal en endodontométrie électronique." Bordeaux 2, 1988. http://www.theses.fr/1988BOR20043.
Claudot, Julien. "Développements et applications de méthodes pour la description de l’énergie de corrélation dans les molécules et les solides." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0073/document.
Commonly used density functionals have encountered a spectacular success in the modelling of physical, chemical or biological systems. However, they have proven to be unsuitable to describe some situations, such as London’s dispersion forces or strong correlation behaviour. In this thesis, we have been interested in recent developments in the formulation of the correlation energy from the adiabatic connection fluctuation dissipation theorem, to overcome these problems. In particular, different implementations of methods beyond the random phase approximation, which allow to take into account the exchange contribution in the computation of the correlation energy, have been compared. Then, in order to drastically decrease the numerical complexity, an orthogonalization procedure of the vectors used to represent the dielectric matrix has been developed. Then these approaches were applied to the calculation of the binding energy of small molecular complexes. The formulation of the correlation energy of the Møller-Plesset perturbation theory within the dielectric matrix context is also presented and tested. In parallel, calculations using numerically efficient semi-empirical methods were conducted over three molecular sets in order to test their performances regarding the binding energies by comparing them to reference values available in the literature
Peltier, Cyril. "Etude théorique de dispositifs moléculaires pour la spintronique." Paris 6, 2010. http://www.theses.fr/2010PA066584.
Haddad, Elias. "Nouvelles approches RMN pour l'étude structurale des matériaux mésoporeux organisés : apport de la RMN du 129Xe hyperpolarisé." Paris 6, 2004. http://www.theses.fr/2004PA066150.
Dridi, Zoulikha. "Les propriétés structurales et électroniques des alliages AlxGa1-xN, InxGa1-xN, et InxAl1-xN : étude par la méthode ab initio des ondes planes augmentées avec linéarisation et potentiel total." Caen, 2003. http://www.theses.fr/2003CAEN2076.
Guggenbuhl, Pascal. "Analyse de textures appliquée au tissu osseux." Rennes 1, 2006. http://www.theses.fr/2006REN1B102.
Poulain, Agnieszka. "Recherche expérimentale de la distribution de la densité électronique dans les cristaux de 4-nitro-imidazolés." Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0025/document.
Fagette, Antoine. "Détection de foule et analyse de comportement par analyse vidéo." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066709.
This thesis focuses on the similarity between a fluid and a crowd and on the adaptation of the particle video algorithm for crowd tracking and analysis. This interrogation ended up with the design of a complete system for crowd analysis out of which, this thesis has addressed three main problems: the detection of the crowd, the estimation of its density and the tracking of the flow in order to derive some behavior features.The contribution to crowd detection introduces a totally unsupervised method for the detection and location of dense crowds in images without context-awareness. After retrieving multi-scale texture-related feature vectors from the image, a binary classification is conducted to identify the crowd and the background.The density estimation algorithm is tackling the problem of learning regression models when it comes to large dense crowds. In such cases, the learning is impossible on real data as the ground truth is not available. Our method relies on the use of synthetic data for the learning phase and proves that the regression model obtained is valid for a use on real data.Our adaptation of the particle video algorithm leads us to consider the cloud of particles as statistically representative of the crowd. Therefore, each particle has physical properties that enable us to assess the validity of its behavior according to the one expected from a pedestrian, and to optimize its motion guided by the optical flow. This leads us to three applications: the detection of the entry and exit areas of the crowd in the image, the detection of dynamic occlusions and the possibility to link entry areas with exit ones, according to the flow of the pedestrians
Sharkas, Kamal. "Développement de nouvelles méthodes hybrides en théorie de la fonctionnelle de la densité par séparation linéaire de l’interaction électronique." Paris 6, 2013. http://www.theses.fr/2013PA066765.
This thesis draws together methodological contributions to the hybrid methods in density functional theory (DFT). The combination of DFT and several wave function methods has been done by linear separation of the electron-electron interaction in the multideterminantal extension of the Kohn-Sham scheme. Aiming at improving the calculation of (near-)degeneracy correlation effects in molecular systems, we have developed the multiconfigurational hybrids which combine DFT with a multiconfiguration self-consistent field calculation. The coupling between DFT and second-order Møller-Plesset perturbation theory (MP2) has provided the theoretical justification and development of double hybrid approximations which have been tested for molecular and extended systems
Desfosses, Ambroise. "Analyse d'images de microscopie électronique de biopolymères hélicoïdaux flexibles." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00945659.
Goglio, Jean-Paul. "Mesure d'orientation cristallographiques par analyse d'images de microscope électronique." Grenoble INPG, 1997. http://www.theses.fr/1997INPG0208.
Bethuel, Fabrice. "Densité des fonctions régulières dans des espaces de Sobolev." Paris 11, 1989. http://www.theses.fr/1989PA112120.
Gendron, Frédéric. "Études théoriques de systèmes moléculaires inorganiques : de la molécule au dispositif." Rennes 1, 2012. http://www.theses.fr/2012REN1S069.
The relationships between the electronic structure of carbon-rich organometallic complexes and their physical properties were rationalized with the aid of density-functional-theory calculations. These molecules constituted of several metal centers have attracted great attention because they can be stable under several oxidation states and display electronic and magnetic communication which are interesting for application in molecular electronics. A particular attention was given to a series of mono-oxidized complexes containing metal atoms of Group 8. These studies showed that the distribution of the atomic spin densities is strongly influenced by the nature of the metal center and the ancillary ligands. These results allowed understanding the EPR measurements of these monocationic systems and their thermodynamic stability. Similar studies were performed on several analogous bi- or tetra-metallic compounds. These studies highlight the preponderant role played by the orientation of the metallic fragments on the electronic communication properties and on the magnetic coupling of these oxidized species. Indeed, rotations of one organometallic end-group with respect to the other can lead to an energetic reorganization of the frontier orbitals which can lead to a change from an antiferromagnetic state to a ferromagnetic state. An innovative approach is to potentially use these systems as molecular building blocks for the design of devices such as switches, molecular wires, molecular memories or quantum cellular automata. A preliminary theoretical study of these molecules grafted on gold surfaces is briefly described
Fathallah, Sofiane. "Étude théorique de la structure électronique et de propriétés physiques d'édifices moléculaires à ponts carbonés." Rennes 1, 2005. http://www.theses.fr/2005REN1S139.
Koutti, Lahcen. "Étude de la densité électronique des phases paramagnétique et antiferromagnétique des monosulfures NiS, CoS et FeS de structure hexagonale dans l'approximation de la densité locale de spin." Metz, 1999. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/1999/Koutti.Lahcen.SMZ9917.pdf.
Li, Feng. "Etude dans l'ionosphère de la densité électronique et de la turbulence électrostatique en fonction de l'activité séismique." Phd thesis, Université d'Orléans, 2007. http://tel.archives-ouvertes.fr/tel-00689864.
Lediankine, Andrei͏̈. "Mesures spectroscopiques de la densité et de la température électronique au bord du plasma dans TORE SUPRA." Aix-Marseille 1, 1996. http://www.theses.fr/1996AIX11043.
Pérès, Nicole. "Contribution à l'étude du phosphate diacide d'ammonium NH4H2PO4 dans sa phase paraélectrique : densité électronique et propriétés optiques." Nancy 1, 1997. http://www.theses.fr/1997NAN10275.
De, Gentile Benoît. "Fluctuations de densité électronique à petite échelle dans un tokamak : aspects statistiques, et liens avec l'activité magnétohydrodynamique." Paris 11, 1987. http://www.theses.fr/1987PA112044.