Comprehension of reactive chemical dynamics in the gas phase and at the gas/organic-surface interface and non-reactive dynamics at the interface between hydrophobic surfaces and water requires an understanding of the fundamental atomic and molecular interactions that undergird these important phenomena. In an effort to study these regimes of chemical interaction, we have performed computational simulations that probe the dynamics of chemical systems that exemplify each of these domains. To study gas-phase chemical dynamics, we reparametrized semiempirical Hamiltonians so that they can accurately describe the potential energy surfaces for two distinct atom+alkane reactions. In addition to their demonstrated accuracy, these methods possess the attractive quality of being computationally inexpensive enough to afford extensive direct-dynamics trajectory studies. Our results on the dynamics of atom+alkane hydrogen-abstraction reactions have shown good agreement with experimental metrics that are as diverse as product velocity distributions, excitation functions, angular distributions and rovibrational state distributions for diatomic products of the abstraction. We have demonstrated that our reparametrized Hamiltonians are suitable for investigating gas-phase reactions with up to 15 (5 heavy) atoms and that they are appropriate for studying reactions beyond the gas phase, especially gas/surface reactions. By employing our semiempirical methods within a quantum-mechanics/molecular-mechanics hybrid scheme we are able to examine hydrogen-abstraction reactions of fluorine atoms with alkanethiolate self-assembled monolayers. Our simulations reproduce the general trends of experimental results for the cousin F+squalane reaction. Our simulations also probe the role that secondary collisions play in determining the final internal and translational energy of the product HF molecules. For instance, we determined that very few interactions with the SAM surface were required to cool rotational and translational modes of the HF product, while its vibrational energy remains unchanged on the time scale that HF molecules trap on the SAM surface. Moving beyond the gas/organic surface interface, we have also performed molecular-dynamics simulations of thin water films confined between hydrophobic SAM surfaces. These simulations illuminated the structural and dynamics behavior induced in the water films by confinement in hydrophobic environments. While most effects of the surface do not penetrate deep into the water layers we have noted that enhanced lateral diffusion of water molecules can persist in these films with > 1 nm length scales. We have elucidated a possible mechanistic precursor for the attractive forces seen in experimental measurement of the hydrophobic effect. / Ph. D.

D’immenses progrès ont été réalisés ces dernières années dans le champ de production de condensats de Bose-Einstein moléculaires pour l’obtention et le piégeage de molécules ultrafroides ioniques et neutres. Ces échantillons de molécules ultrafroides trouvent des applications dans des domaines très variés tels que les mesures pectroscopiques de haute précision ou bien encore le stockage de l’information quantique. La volonté d’optimiser les procédés de refroidissement et des techniques de piégeage a stimulé un grand nombre d’études théoriques. La plupart de ces études sont dédiées au refroidissement des molécules en collision avec un gaz tampon (3 He). La surface d’énergie potentielle de l’état fondamental du complexe de van der Waals He–MnH(X7Σ+) est présentée, suivie du calcul des états liés correspondant au complexe ainsi que l’étude de la relaxation Zeeman associée au système en fonction du champ magnétique appliqué. Dans le domaine de l’astrochimie, l’étude de la désexcitation rotationnelle de CH+ en collision avec l’hélium est également présentée. / Tremendous progress in experimental production and trapping of ultracold neutral and ionic molecules has been achieved over the past few years which even allowed the production of molecular Bose–Einstein condensates. These ultracold molecules samples have potential applications in many different fields, such as precision spectroscopic measurements or quantum information storage and processing. The optimization of the cooling processes and the trapping techniques also stimulated a great number of theoretical studies. Many of them are dedicated to inelastic scattering of molecules in collisions with 3He atoms (buffer gas cooling method). The potential energy surface of the ground state of the He–MnH(X7Σ+) van der Waals complex is presented, followed by the calculations of the bound states of this system and the Zeeman relaxation in function of the magnetic field. In the field of astrochemistry, a quantum mechanical investigation of rotational energy transfer in cold collisions of CH+ with 4He atoms is presented.

<p>Disertacija daje pregled novih i relevantnih istraživanja i stavova<br />u naučnoj zajednici na temu štamparskih formi i uticaja procesa<br />štampe na trošenje neštampajućih elemenata. U disertaciji je<br />ukazano na kontinualno praćenje topografskih promena<br />neštampajućih elemenata štamparskih formi kako bi se kontrolisao<br />period eksploatacije a time i proces reprodukcije. Takođe daje<br />prilog novim istraživanjima sa analizom velikog broja<br />eksperimentalnih uzoraka sa dobijenim izmerenim podacima i<br />odgovarajućim korelacijama i predstavlja napredak u shvatanju<br />mehanizma trošenja neštampajućih površina štamparskih formi i<br />njihov uticaj na tribološke promene u odnosu na strukturu osnove<br />aluminijuma i sloja aluminijum oksida.</p> / <p>Dissertation gives an overview of the current state, research and theories of<br />printing forms and influence of printing process on wearing of non-printing<br />elements within the science community. The dissertation points out the continuous<br />monitoring of topographic changes of printing form non-printing elements to control<br />the exploitation of a period of time and the process of reproduction. This work<br />contributes to new research with the analysis of large number of experimental<br />samples and calculated correlations and represents an advance in the<br />comprehension of the surface wear mechanism of printing form non-printing<br />elements and their influence on the tribological changes to the structure of the<br />base layer of aluminium and aluminium oxide.</p>

Ma thèse de doctorat doit contribuer à la diminution du gaspillage des ressources naturelles (en particuliers les sables naturels) en étendant leur acceptabilité dans les enrobés bitumineux. La compréhension de l’effet des particules nocives, notamment la fraction argileuse contenue dans les sables, sur le comportement des mélanges bitumineux est visé. Pour évaluer le niveau de nocivité des particules fines, le test d'adsorption du bleu de méthylène noté MB (EN13043, NF EN 933-9) est appliqué, mais un tel test a été modifié à quatre reprises au cours des 22 dernières années tandis que la valeur de bleu limite, utilisée pour déterminer la conformité ou non du sable, n’a pas été modifiée. Le projet de thèse vise à modifier cette valeur limite pour étendre la gamme de sable utilisable. Cet objectif sera atteint grâce à l’identification de la composition minéralogique des sables, une recherche sur la meilleure manière de quantifier les phases qui composent les sables et une meilleure compréhension du rôle de la fraction fine sur la durabilité et les pathologies des mélanges bitumineux. Le travail de thèse est organisé en différentes tâches : 1. Tester le protocole de mesure de la valeur de bleu. Nous voulons comprendre l'effet de différents facteurs (tels que l'échantillonnage, la cinétique des additions de bleu, la température de séchage du sable avant l’essai ...) sur la mesure de la valeur de bleu. Le développement d'un appareil automatique ou d'une nouvelle méthode (qui sera validée par comparaison avec les résultats obtenus à partir de la méthode standardisée) est prévu.2. Établir une corrélation entre la valeur de bleu (ou d'autres paramètres à trouver) et la quantité de phases minérales présentes dans les sables. Un jeu de données a d’ores et déjà été établi au cours de mon stage de master. Pour atteindre cet objectif, les différentes méthodes de quantification (utilisant en particuliers la diffraction de rayons X) doivent être testées et comparées.3. Corréler la valeur de bleu couplée à la nature minéralogique des particules fines avec le comportement mécanique des mélanges sable/bitume. Nous allons étudier la dégradation en présence d’eau des propriétés du matériau bitumineux (par exemple l'adhésion du liant bitumineux sur granulat) et le rôle de la couche de particules fines qui entourent les grains de sable sur les propriétés mécaniques de ce matériau. Nous espérons comprendre en particulier l'effet de la présence d’argile gonflante dans les matériaux constitutifs de la chaussée bitumineuse.4. Améliorer le comportement des granulats non conformes par l’application d’un traitement. Après l'identification de l'origine des pathologies (nous faisons l'hypothèse que les argiles gonflantes jouent un rôle majeur), nous proposons d'appliquer un traitement en ajoutant de la chaux (ou de traiter en ajoutant des déchets qui contiendraient des substances actives comme la chaux), et de tester également l’utilisation de polymères ou du greffage avec des composés organiques des argiles comme traitement / Siliceous fines (clays) in fine aggregates used for AC pavement stimulate the moisture entering the bitumen-aggregates interface in AC mixture and create channels for water penetration. MB adsorption for qualifying fine aggregates is in accordance with the layer charge and the accessibility of consisted mineralogy in fine aggregates. However, the correlation between MB qualification for fine aggregates and fine aggregates triggering moisture susceptibility of AC mixture has not ever been addressed; moreover, the questions from MB adsorption still remain to be solved. In order to evaluate the stripping and to clarify MB adsorption on fine aggregates from a mineralogical perspective, the most common clays in natural aggregates, kaolinite, illite and montmorillonite, were extracted from their clay rocks, and used to prepare thin clay film, artificial fine aggregates and asphalt concrete mixtures consist of artificial fine aggregates. Moreover, the 5 blinded fine aggregates received from quarries without any given information were applied as the blinded experiments to confirm the practicability with mineralogical diversity. The mineralogical analysis was identifying and quantifying the mineral phases in extracted clay and fine aggregates by using X-Ray diffraction, and the quantitative results were judged by complementary test. MB adsorption was studied using drop method, UV-Photometer method and cation exchange capacity from clays and aggregates. Water-bitumen-clay interaction was studied using the sessile drop and the Oliensis spot tests on those thin clay films. The water intrusion routes in AC mixture was investigated immersing AC mixture in solution with chemical probe, whereas Duriez tests allowed measuring the moisture susceptibility of AC mixtures containing varied clay mineralogy in fine aggregates. The results show that clay mineralogy is in relation to water-bitumen-clay interaction, and it is agreed by moisture susceptibility of AC mixture indicated by Duriez test. With the dispersive nature bitumen used in this study, cohesive failure is in the light of kaolinite-AC mixture in the presence of water, whereas swelling property is responsible for the stripping in illite- and montmorillonite- AC mixture. In order to exclude the physical interferences on MB adsorption, the vale of 100% of MB adsorption on fine aggregates referred to CEC value is necessary to apply, and MB value measured from drop method efficiently excludes the significant impacts from layer charge, pH value and exchangeable cations. Although MB adsorption is in relation to clay mineralogy, this test does not sufficiently indicate the stripping of AC mixture occurred by clay in fine aggregates. There are still rooms to use the non-qualified fine aggregates for the use of AC pavement. As Rietveld method from X-Ray diffraction derives the most reasonable quantitative results, the X-Ray powder diffraction and the X-Ray orientated EG treated K-saturated clay diffraction are proposed for analyzing clay mineralogy and its swelling property for judging the use of non-qualified fine aggregates for AC mixture.MB2 and Duriez0.8 surfaces can be established on clay mineralogical map since we discovered MB adsorption and moisture susceptibility are related to clay mineralogy in fine aggregates. The fine aggregates which is not qualified by MB adsorption is going to confirm the possibility for the use of AC pavement by the mineralogical analysis through X-Ray diffraction. By adopting the quantitative results of clay on mineralogical map with Duriez0.8 surface and the swelling property of clays in fine aggregates, the use of fine aggregates for AC pavement can be properly judged according to water-bitumen-aggregates interaction and stripping which has been proved in this study

Le but principal de ce travail est d'examiner la capacité des méthodes clusters couplés explicitement corrélées (CCSD(T)-F12) pour la génération des surface de potentiel (SEPs) multidimensionnelles à courte, moyenne et longue portée intermoléculaires et leur utilisation dans la détermination des spectres des systèmes van der Waals (vdW) et des données de collision sur une large gamme d'énergie de collision. Ceci a été fait par une comparaison directe des surfaces de potentiel et des résultats générés à partir de l'utilisation des méthodes clusters couplés standards avec simple, double et un traitement perturbatif des excitations triples (CCSD(T)) et explicitement corrélée CCSD(T)-F12. En effet, nous démontrons que la méthode CCSD(T)-F12 en connexion avec la base aug-cc-pVTZ est la méthode de choix pour la génération de ces surfaces de potentiel avec une très grande réduction du coût computationnel (temps CPU et occupation disque). Ceci est illustré à travers l'étude des systèmes vdW HCl/DCl-He et CO2 -CO2 qui sont importants pour l'astrophysique et les atmosphères planétaires. Pour HCl/DCl-He, nous avons comparé les résultats issus des SEPs explicitement corrélées et celles calculées avec les méthodes cluster couplés standards. Ces SEPs ont été générées le long des coordonnées intermonomères. A travers ces comparaisons, nous avons montré que l'utilisation des méthodes CCSD(T)-F12/aug-cc-pVTZ explicitement corrélées permet de dépasser la précision de l'approche CCSD(T)/CBS (prise comme référence) avec un coût computationnel très réduit. La qualité de la surface de potentiel explicitement corrélée a été vérifiée par le calcul des sections efficaces et des taux de collision d'excitation rotationnelle de HCl/DCl par He. Par la suite, Nous étendons, notre étude aux systèmes moléculaires plus larges à travers l'étude du dimère de dioxyde de carbone,(CO2 )2 . Ainsi, nous avons généré une SEP d'interaction à 4 dimensions pour le dimère de dioxyde de carbone (CO2 )2 en utilisant la méthode CCSD(T)-F12/aug-cc-pVTZ qui a été comparée avec d'autres surfaces et spécialement avec celle générée par les approches de référence CCSD(T)/CBS et SAPT. Cette comparaison a bien prouvé la performance des méthodes explicitement corrélées pour la description de la corrélation électronique. Ceci, a été validé par des calculs de dynamique qui ont permis de déterminer le second coefficient du viriel, le premier moment spectral et les niveaux vibrationnels du dimère de CO2 et leur comparaison aux résultats expérimentaux et théoriques existants. Nous recommandons donc l'utilisation de la méthode CCSD(T)-F12/aug-cc-pVTZ pour l'étude des interactions moléculaires impliquant des systèmes polyatomique-polyatomique faiblement liés / The main goal of this work is to examine the capabilities of explicitly correlated coupled cluster (CCSD(T)-F12) methods for the mapping of multidimensional potential energy surfaces (PESs) at short, medium and long intermolecular ranges and therefore their use in the determination of accurate collisional data for a wide range of collision energies after dynamical computations. This is done through close comparisons of these PESs and corresponding data to those deduced using standard coupled cluster approaches with perturbative treatment of triple excitations (CCSD(T)). Therefore, we definitely establish that CCSD(T)-F12 in connection with the aug-cc-pVTZ basis set is the method of choice for the generation of such accurate PESs with strong reduction of computational cost (CPU and disk occupancy). As a benchmark, we treated the rotational excitation induced by collision of HCl/DCl-He and CO2 -CO2 van der Waals molecular systems, which are relevant for astrophysics and planetary atmospheres, respectively. For HCl-He and DCl-He, we closely compared the results deduced from PESs calculated with explicitly correlated and standard coupled cluster methods. These PESs were generated over the intermonomer degrees of freedom. Through these comparisons, we have shown that the use of explicitly correlated CCSD(T)-F12/aug-cc-pVTZ method overcomes the accuracy of the reference approach CCSD(T) associated with the complete basis set (CBS) with a very low computational cost (2 orders of magnitude less). The quality of the explicitly correlated potential surface was verified by cross sections and collision rate calculations. Then, we extended our findings to the CO2 -CO2 larger molecular systems. Hence, we generated four-dimentional (4D) PES of the carbon dioxide dimer (CO2 )2 using the CCSD(T)-F12 method and we compared it with other surfaces specially with that generated by the CCSD(T)/CBS and SAPT approaches. Again, we established the performance of explicitly correlated method to account fully for electron correlation. This was validated after dynamical calculations, where second virial coefficient, first spectral moment and vibrational energies of the CO2 dimer were computed and compared to previous experimental and theoretical data. In total, we recommend the use of CCSD(T)/aug-cc-pVTZ method for the investigation of weak interactions occurring between polyatomic-polyatomic systems for a wide range of applications

No description available.

Heterogenní katalýza hraje významnou roli pro zvy¹ování efektivity rùzných procesù. Vysokou katalytickou aktivitu vykazují oxidy ceru patøící k tzv. reducibilním oxidùm, je¾ snadno uvolòují èi (zpìtnì) pøijímají atomy kyslíku prostøednictvím procesù redukce a oxidace. Zámìrem pøedlo¾ené práce je vypoèítat pásové struktury a øezy plochami konstantní energie objemových a povrchových systémù oxidu ceru pomocí kvantovì-mechanické "ab initio"metody Teorie hustotního funkcionálu. Numerické simulace jsou provádìny pomocí programového balíèku Quantum ESPRESSO za u¾ití metod rovinných vln a pseudopotenciálu. Silná korelace elektronù v pøípadì atomù ceru je modelována pøidáním Hubbardova U-èlenu. Hlavní dùraz je kladen na mo¾nost porovnávání teoretických výsledkù s tìmi získanými pomocí experimentální metody úhlovì-rozli¹ené fotoelektronové spektroskopie umo¾òující pøímý zisk jak pásových struktur, tak øezù plochami konstantní energie zkoumaného materiálu. Porovnání pomù¾e jak poznat mo¾nosti a mo¾né hranice zmínìné experimentální metody, tak i roz¹íøit její teoretické zázemí vedoucí k prohloubení znalostí materiálù perspektivních pro katalýzu. Klíèová slova: Teorie hustotního funkcionálu, Hubbardùv U-èlen, pásová struktura, plocha konstantní energie, Brillouinova zóna 1

No description available.

The rapid neutron-capture process, known as the r-process, is responsible for the origin of about half the stable nuclei heavier than iron observed in nature. Though the r-process is believed to take place in explosive stellar environments and to involve a large number (few thousands) of exotic nuclei, this nucleosynthesis process remains poorly understood from the astrophysics as well as nuclear physics points of view. On the nuclear physics side, the nuclei are too exotic to be studied in the laboratory, even though great efforts are constantly made to extend the experimental limits away from the eta-$stability region. Therefore, theoretical models are indispensable to estimate the nuclear properties of interest in the r-process nucleosynthesis modelling. So far, models used to predict the properties of the exotic nuclei were based on parametrized macroscopic-type approaches the reliability of which is questionable when extrapolating far away from the experimentally known region. This work is devoted to the improvement of nuclear predictions, such as the nuclear ground- and excited-state properties, needed as input data to model the r-process. In order to give the predictions a reliable character, we rely on the microscopic mean-field Hartree-Fock theory based on the Skyrme-type interaction. Pairing correlations play an important role in the description of nuclei, and become essential for nuclei located near the drip lines, since the scattering of pairs of quasi-particles into the continuum increases significantly. In this work, we brought to the Hartree-Fock model the self-consistent treatment of the pairing correlations within the Hartree-Fock-Bogoliubov (HFB) theory. Further improvements are made in the restoration of symmetries broken by correlations added in the form of additional degrees of freedom in the wave function. These include the translational invariance restored by calculating the recoil energy, the particle-number symmetry by an exact projection after variation, the rotational symmetry by an approximate cranking correction and the parity symmetry for reflection asymmetric shapes. In addition, the renormalization of the HFB equations has been studied as well and allows to eliminate the dependence of the total energy with respect to the cutoff energy. The effective nucleon-nucleon interaction is determined by adjusting its parameters on all available experimental masses, with some constraints derived from fundamental nuclear matter properties. A systematic study of the influence on mass predictions for each of the above cited improvements as well as of some uncertainties affecting the particle-hole and particle-particle interactions has been conducted. In spite of quite important differences in the input physics, we find a great stability in the mass predictions for exotic neutron-rich nuclei, though local mass differences can be significant. Each of the Skyrme force derived in the present work has been tested on the predictions of basic ground-state properties (including charge radii, quadrupole moments, single-particle levels), fission barriers and electric dipole $gamma-$ray strengths. The HFB predictions globally reproduce experimental data with a level of accuracy comparable with the widely-used droplet-like models. The microscopic character of the approach followed in the present work makes however the predictions for exotic neutron-rich nuclei involved in the r-process more reliable. The influence of such improved nuclear mass predictions on the r-process abundance distribution is studied in the specific scenario of the prompt supernova explosion mechanism.

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal.