Дисертації з теми "Quantum Clusters"
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Gregory, J. "Quantum simulation of water clusters." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599693.
Повний текст джерелаMouhat, Félix. "Fully quantum dynamics of protonated water clusters." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS056/document.
Повний текст джерелаThere is no theory up to now able to provide an accurate and quantitative description of the proton transfer (PT) yet. Indeed, the complexity of the problem stems from the large diversity of the existing interactions in liquid water, namely: non bonding Van der Waals interactions, weakly covalent bonds and remarkably strong H-bonds. The latter ones are at the origin of the numerous fascinating properties of water at the macroscopic scale. In addition to such interactions, the nuclear quantum effects arising from the hydrogen light mass deeply modify the potential energy surface, and must be taken into account. In this thesis, we propose a fully quantum approach based on an almost exact description of the electronic wave function by means of Quantum Monte Carlo (QMC) methods. Our novel technique combines QMC with a Langevin-based Molecular Dynamics and the Feynman's path integral formalism. This allows one to perform fully quantum simulations of systems in gas or condensed phase, at an unprecedented level of accuracy,. We apply our approach to neutral or charged protonated water clusters to shed light on the microscopic phenomena driving the proton diffusion in such systems. We discovered that the proton hopping is optimal for temperatures close to ambient conditions, due to the subtle competition between thermal and nuclear quantum effects. This is highly suggestive of the importance of quantum nuclear effects to make PT processes - relevant for life - most efficient at room temperature
Schmidt, Karl. "Factorizable Module Algebras, Canonical Bases, and Clusters." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23793.
Повний текст джерела鄒鳳嬌 and Fung-kiu Chow. "Quantum statistical mechanics: a Monte Carlo study of clusters." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B31224258.
Повний текст джерелаBenoit, David Michel. "Diffusion Quantum Monte Carlo simulations of hydrogen-bonded clusters." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313057.
Повний текст джерелаAlbring, Morten. "Towards quantum information processing with Cr3+ based heterometallic clusters." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/towards-quantum-information-processing-with-cr3-based-heterometallic-clusters(6ff7e303-ca75-4632-986d-48bea42d96e3).html.
Повний текст джерелаChow, Fung-kiu. "Quantum statistical mechanics a Monte Carlo study of clusters /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22424799.
Повний текст джерелаReid, Adam. "Quantum tunnelling splittings in water clusters, from ring-polymer instanton theory." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.709028.
Повний текст джерелаVaranasi, Mohan R. "Geometries of small cadmium selenide (CdSe) clusters." Virtual Press, 2006. http://liblink.bsu.edu/uhtbin/catkey/1349770.
Повний текст джерелаDepartment of Physics and Astronomy
Dai, Yafei. "Quantum and classical studies of calcium and zinc clusters and of pyrrole oligomers." Fairfax, VA : George Mason University, 2009. http://hdl.handle.net/1920/3448.
Повний текст джерелаVita: p. 131. Thesis director: Estela Blaisten-Barojas. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computational Sciences and Informatics. Title from PDF t.p. (viewed June 10, 2009). Includes bibliographical references (p. 125-130). Also issued in print.
Ye, Xinying. "SEMI-AUTOMATIC AND INTERACTIVE VISUALIZATION OF QUANTUM DOT NANO-STRUCTURES." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1195496291.
Повний текст джерелаCasalenuovo, Kristen. "Density Functional Investigations of Pure and Ligated Clusters." VCU Scholars Compass, 2009. http://scholarscompass.vcu.edu/etd/1788.
Повний текст джерелаSkrbic, Tatjana. "Dynamics of doped [4]He and [3]He clusters from reptation quantum Monte Carlo." Doctoral thesis, SISSA, 2009. http://hdl.handle.net/20.500.11767/4779.
Повний текст джерелаBürgel, Christian. "Functionality of noble-metal clusters." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2009. http://dx.doi.org/10.18452/15887.
Повний текст джерелаIn this thesis, the unique novel properties of noble metal clusters which arise in the sub-nanometer size regime due to quantum confinement have been theoretically explored. It has been demonstrated that by adding or removing a single atom the chemical and physical properties and functionality of noble-metal clusters can strongly change. The theoretical results have been derived in close cooperation with experimental findings of partner groups demonstrating that by joint theoretical and experimental efforts thorough understanding of fundamental processes and underlying mechanisms can be achieved. This thesis addresses the reactivity of charged gas-phase gold-oxide clusters in the context of the heterogeneous gold nano-catalysis, the ultrafast dynamical properties of noble-metal clusters and their complexes, and the optical properties of silver clusters at surfaces.
Pichugin, Kostyantyn. "ELECTRONIC STRUCTURE AND REACTION DYNAMICS OF MOLECULAR AND CLUSTER ANIONS VIA PHOTOELECTRON IMAGING." Diss., The University of Arizona, 2010. http://hdl.handle.net/10150/194339.
Повний текст джерелаWu, Lu. "STRUCTURES AND ELECTRONIC STATES OF SMALL GROUP 3 METAL CLUSTERS." UKnowledge, 2014. http://uknowledge.uky.edu/chemistry_etds/32.
Повний текст джерелаWang, Ruizhe. "Magnetic fluctuations and clusters in the itinerant ferromagnet Ni-V close to a disordered quantum critical point." Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1555936445433091.
Повний текст джерелаAverkiev, Boris. "Geometry and Electronic Structure of Doped Clusters via the Coalescence Kick Method." DigitalCommons@USU, 2009. http://digitalcommons.usu.edu/etd/408.
Повний текст джерелаNorth, Stephen Michael. "Electronic structure of GaSb/GaAs and Si/Ge quantum dots." Thesis, University of Newcastle Upon Tyne, 2001. http://hdl.handle.net/10443/551.
Повний текст джерелаBhowmick, Somnath. "Theory on lower bound energy and quantum chemical study of the interaction between lithium clusters and fluorine/fluoride." Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM4394.
Повний текст джерелаIn quantum chemistry, the variational principle is widely used to calculate an upper bound to the true energy of an atomic or molecular system. Methods for calculating the lower bound value to the energy exist but are much less known. An accurate method to calculate such a lower bound would allow to provide a theoretical error bar for any quantum chemistry method. We have applied variance-like methods to calculate different lower bound energies of a hydrogen atom using Gaussian basis functions. The upper bound energy is found to be always more accurate than the lower bound energies, i.e. closer to the exact energy. The importance of singular points on mean value evaluation of quantum operators has also been brought to attention.The adsorption reactions of atomic fluorine (F) and fluoride (F$^-$) on small lithium clusters Li$_n$ (n=2-15) have been investigated using accurate quantum chemistry ab initio methods. For the smallest system, we have shown that the formation of the stable Li$_2$F and Li$_2$F$^-$ complexes proceeds via a barrierless long-range electron transfer, from the Li$_2$ to F for the neutral and conversely from F$^-$ to Li$_2$ for the anionic system. Such reactions could be fast at very low temperature. Furthermore, the formed complexes show unique long bond characteristics. For the bigger Li$_n$F/Li$_n$F$^-$ systems ($n\geqslant 4$), we have shown that the adsorption energies can be as large as 6~eV depending on the adsorption site and that more than one electronic state is implied in the adsorption process. The formed complexes show interesting "superalkali" properties and could serve as building blocks in the synthesis of charge-transfer compounds with tunable properties
Paolini, Stefano. "Rotational dynamics of molecular impurities solvated in 4He clusters. A computational study based on reptation quantum Monte Carlo." Doctoral thesis, SISSA, 2006. http://hdl.handle.net/20.500.11767/4042.
Повний текст джерелаCrous, Werner. "The evaluation of the ONIOM-EE method for the QM/MM hybrid modeling of HF, CO and CO/HF Clusters." Thesis, Stellenbosch : Stellenbosch University, 2006. http://hdl.handle.net/10019.1/21774.
Повний текст джерелаENGLISH ABSTRACT: Quantum mechanics is the method of choice when it comes to the accurate modeling of single molecules and clusters. The correlation energy is the single most important aspect when studying clusters computationally, and reproducing the correlation energy accurately poses a bigger challenge to the computational chemist than in the modeling of single molecules. Very high levels of theory and large basis sets need to be used. Nevertheless, since the calculation of large systems, such as crystals and biological systems, is generally beyond the capacity of quantum mechanics, molecular mechanics is generally used for these systems. Unfortunately due to its nature, molecular mechanics cannot model important quantum effects, but this problem can be solved by a hybrid system in which one part of the system is treated by quantum mechanics and the remaining part by molecular mechanics. In order to combine quantum mechanics with molecular mechanics one needs to optimize the parameters for the molecular mechanics part to allow it to function with the quantum mechanics. The research described in this work is based on the ONIOM-EE method, which is such a hybrid method. In this work we investigate the applicability of the ONIOM-EE method in modeling hydrogen fluoride, carbon monoxide and CO/HF clusters. Most of the clusters’ geometries in this work are not experimentally or computationally known. We therefore perform a computational analysis of all of the clusters by using various methods including Atoms in Molecules, Natural Bond Orbital analysis, Mulliken population analysis and the analysis of delocalized molecular orbitals to obtain information for the development of hybrid systems. During this process we look at different charge derivation schemes and at two different methods of optimizing force field parameters for these clusters. We develop a method to make force field optimization faster and better for specific hybrid systems. This method showed that in all cases the optimized parameters were an improvement on those of the Universal Force Field. We show the importance of an accurate description of the electrostatic interactions in HF, CO and CO/HF clusters and that this is the Achilles heel when attempting to optimize van der Waals parameters for force fields. We further show that atomic point charges are not a good approximation of a molecules’ charge density in hybrid methods. In addition, we make suggestions on how the present method for ONIOM-EE can be improved to make the modeling of van der Waals clusters feasible.
AFRIKAANSE OPSOMMING: Kwantum meganika is die metode van keuse wanneer enkele molekule en molekulêre sisteme op rekenaar gemodeleer moet word. Dit is egter bekend dat die modelering van molekulêre sisteme ’n groter uitdaging stel aan die molekulêre modeleerder, aangesien baie hoë vlakke van teorie en groot basisstelle gebruik moet word om die korrelasie-energie, rekenkundig te produseer. Die akkurate herprodusering van die korrelasie-energie is seker die heel belangrikste vereiste waaraan voldoen moet word as molekulêre sisteme d.m.v. ’n rekenaar gemodeleer word. Nietemin is dit onprakties om kwantum meganiese metodes te gebruik vir groot sisteme soos kristalle of biologiese molekule en juis om dié rede word molekulêre meganika meestal ingespan vir sulke gevalle. Molekulêre meganika is egter ondoeltreffend om belangrike kwantumeffekte te modeleer. Tog is daar ’n oplossing vir hierdie probleem in die vorm van ’n hibried sisteem waar een deel van die sisteem met kwantum meganika en die oorblywende deel van die sisteem met molekulêre meganika behandel word. Om dit moontlik te maak om molekulêre meganika met kwantum meganika te kombineer, moet parameters vir die molekulêre meganika deel geoptimiseer word sodat dit saam met die kwantum meganiese deel kan funksioneer. Die navorsing wat in hierdie studie beskryf word is gebaseer op so ’n hibriedmetode wat bekend staan as ONIOM-EE. In hierdie studie bestudeer ons die moontlikheid om ONIOM-EE te gebruik vir die modelering van molekulêre sisteme van waterstoffluoried, koolstofmonoksied en CO/HF sisteme. Die meeste van die sisteme, wat in hierdie studie behandel word, se strukture is onbekend, beide in terme van eksperimentele gegewens en molekulêre modelering. Ons voer dus ’n volledige analise van al die sisteme uit deur van verskeie metodes soos “Atoms in Molecules”, “Natural Bond Orbital” analise, Mulliken populasie analise en die analise van gedelokaliseerde molekulêre orbitale, gebruik te maak. Dit stel ons in staat om ’n hibriedsisteem te ontwikkel vir die molekulêre sisteme. Gedurende die proses ondersoek ons ook die gebruik van verskillende ladingsafleidings-sisteme en twee metodes word ondersoek waarop ’n kragveld vir ’n hibriedsisteem geoptimiseer kan word. Ons toon aan dat die geoptimiseerde parameters beter resultate lewer as die van die “Universal Force Field” en lig ook die belangrikheid daarvan uit dat die elektrostatiese interaksies se beskrywing ’n hibriedsisteem se Achilles hiel is indien van der Waals parameters geoptimiseer moet word. Ons toon aan dat die gebruik van puntladings op atome om die ladingsdigtheid in molekulêre sisteme te beskryf, ’n onakkurate benadering is. Sekere aanbevelings hoe om die ONIOM-EE metode sodanig te verbeter, dat dit wel gebruik kan word om van der Waals sisteme suksesvol te modeleer, word ook gemaak.
El-Khawaldeh, Amir Verfasser], Hans-Jörg [Akademischer Betreuer] [Kull, and Dieter [Akademischer Betreuer] Bauer. "Quantum Vlasov theory of Mie oscillations in metal clusters : a self-consistent approach to quantum surface effects in nanoparticles / Amir El-Khawaldeh ; Hans-Jörg Kull, Dieter Bauer." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171818513/34.
Повний текст джерелаEl-Khawaldeh, Amir [Verfasser], Hans-Jörg [Akademischer Betreuer] Kull, and Dieter [Akademischer Betreuer] Bauer. "Quantum Vlasov theory of Mie oscillations in metal clusters : a self-consistent approach to quantum surface effects in nanoparticles / Amir El-Khawaldeh ; Hans-Jörg Kull, Dieter Bauer." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1171818513/34.
Повний текст джерелаMello, Victor Giovanni Pina de. "Cálculo da energia de correlação de pequenos clusters de lítio via teoria da informação." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/4940.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
In this dissertation, we use the information theory to obtain the correlation energy of small lithium clusters. Unlike conventional methods for calculation of the correlation energy, the method used here requires only a single calculation in a Hartree-Fock level. With this calculation we obtain a total information energy of the clusters, through the addition of information energy of each atom of the cluster. The correlation energy is a bilinear function of the information energy and number of electrons in the cluster. In order to obtain a general equation for the correlation energy, we use the correlation energy expression that has been obtained through the information theory to t the exact energy of the system using a Monte Carlo quantum simulation of clusters ranging from 1 to 8 lithium atoms. The e ciency of the general equation for the correlation energy has been veri ed through the calculation of the binding energy for clusters of up to 9 and 10 atoms which have not been used in the obtained t. The obtained values for the binding energies are in good agreement with the experimental measurements using photoelectron spectroscopy.
Nesta dissertação obtemos a energia de correlação de pequenos clusters formados por átomos de Lí tio via teoria da informa ção. Diferentemente dos m étodos usuais para o c álculo da energia de correlação, o m étodo aqui utilizado requer somente um c álculo no n ível Hartree-Fock. Deste c álculo se obt em a energia de informação do cluster atráv es da soma das energias de informação dos átomos individuais do cluster. A energia de correlação e uma função bilinear da energia de informa ção e do n úmero de el étrons no cluster. A m de obter uma expressão geral para a energia de correla ção dos clusters de L tio, n os ajustamos a expressão obtida com seus respectivos coe cientes a energia exata deste sistema, calculada usando a simula ção de Monte Carlo quântico para clusters variando de 1 a 8 atomos. A veri cação dessa expressão para a energia de correla ção foi avaliada para clusters maiores não usados no ajuste atrav es do c álculo da energia de liga ção (para cluster de 9 e 10 átomos), os resultados indicam valores em bom acordo com as medidas experimentais usando espectroscopia de fotoel etrons.
Besse, Larissa Zibordi. "Estudo da adsorção de hidroxila, água e etanol sobre clusters de metais de transição com 13 átomos." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/75/75134/tde-18082015-103454/.
Повний текст джерелаThe choice of the catalyst in steam reforming of ethanol process has a central hole in determining the hydrogen production efficiency, used in fuel cells. Transition-metal (TM) surfaces are commonly used as catalysts, but experimental results have shown that TM clusters supported on oxides are more efficient and more selective than their macroscopic analogues. Therefore, to understand the mechanism of interaction between ethanol and water, and also the hydroxyl radical (simple characterization for the O-H bonding) with TM13 magic clusters (TM = Ni, Cu, Pd, Ag, Pt and Au), we performed ab initio calculations based on density functional theory within the functional proposed by Perdew-Burke-Ernzerhof (PBE) and Tkatchenko-Scheffler approach for van der Waals corrections (vdW). The Kohn-Sham orbitals were expanded by numerical atom-centered orbitals (NAOs), which are implemented at the Fritz Haber Institute - ab initio molecular simulations package (FHI-AIMS). We found that clusters 3d and 4d prefer more compact configurations, while Pt13 and Au13 systems adopt more open geometries. In particular case of Au13, our lowest energy configuration is a planar structure, while the first high energy isomer is a 3D configuration. For adsorption calculations, we selected the lowest energy configurations (LOW), and the icosahedral clusters (ICO). We observed that the hydroxyl (OH) has no adsorption site preference and also it does not show a geometric trend, while water and ethanol preferentially bind via oxygen at the top site. In the case of ethanol, it is also possible to find isomers with higher energies, which bind via hydrogen from CH group, and they are probable at room temperature. OH has an electron unpaired, which favors the formation of chemical bonds between the molecule and TM13, so that the adsorption energy varies from -4.11 to -2.94 eV, consistent with charge transfer from cluster to the molecule. When we compare the water and ethanol adsorption on surfaces TM(111) and on TM13, we note that the adsorption energy, that follows the order 3d > 4d > 5d for MT(111), is higher compared to the clusters energy. For water (ethanol), this property varies between -255 meV (-317 meV) < -Ead < -670 meV (-837 meV); however, the magnitude of the interaction occurs in the order 3d > 4d, but also 4d < 5d. The breaking of the trend can be explained by size effects, that enhances the catalytic activity of platinum and gold clusters. It is also observed that the stronger interaction between molecules and TM13 with d-orbitais partly occupied, since these metals provide a higher rearrangement of the electron density. There is a small charge transference from water and ethanol molecules to the clusters, pointing to the weak interaction. Vibrational calculations support the structural and energetic changes that occur in the system, where νO-H increases for the hydroxyl and decreases to water and ethanol.
Oswald, Sönke. "Weak Hydrogen Bonds to Molecular Nitrogen and Oxygen as Experimental Benchmarks for Quantum Chemistry." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/11858/00-1735-0000-002E-E5E0-3.
Повний текст джерелаZhang, Qi. "The fabrication and characterisation of quantum dots, wires and wire net works." Thesis, De Montfort University, 1996. http://hdl.handle.net/2086/4182.
Повний текст джерелаChaves, Anderson Silva. "Estudo teórico das propriedades estruturais, eletrônicas e reatividade de clusters de metais de transição." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-24042015-083608/.
Повний текст джерелаSub-nanometre sized transition metal (TM) clusters have attracted great attention due to their unique physical and chemical properties, very different from the bulk counterparts. These unusual properties can vary with size, composition and state of charge for gas-phase clusters. An in-depth understanding of the properties evolution in function of such parameters is a necessary prerequisite to leverage diverse applications, from catalysis to magnetic storage, as well as to answer fundamental questions related with the intrinsic stability of these systems. However, this understanding is not yet satisfactory. In this project, using first-principles calculations based on density functional theory within the generalized gradient approximation in the formulation proposed by Perdew-Burke-Ernzerhoff, we investigate the atomic structures, electronic properties and stability of all TM (30 elements) unary clusters in function of size (2 – 15 atoms). To study the influence of the charge we considered Cun and Ptn (n = 2 – 14) clusters in the cationic, neutral and anionic states, while compositional effects were considered for bimetallic PtnCum–n clusters with m = 2,3, · · · ,14 and n = 0,1, · · · ,m. Our results suggest that: (i) The stabilization mechanisms for unary clusters are based on the nature of chemical bondings, on which the occupation of the bonding or antibonding d orbitals and the s – d hybridization strongly affect the properties. For example, most magic TM clusters are accompanied by peaks in s – d hybridization and null electric dipole moments.(ii) Different parameters affect TM cluster structures in that size regime, such as, free-atom properties, magnetic exchange interactions and relativistic effects. (iii) The properties are very susceptible to the charge state; in particular, the structures tend to decrease the atomic coordination when one electron is added to the system, which strongly affects the 2D-3D transition. (iv) Negative excess energy was obtained for the most PtCu clusters, which provides a strong evidence for the formation of these bimetallic clusters. Moreover, our analyzes suggest that the formation of core(Cu)-shell(Pt) like structures starts at this size regime, in order to release strain energy. (v) The center of gravity of the occupied d states of the Pt–Cu alloy vary with composition and approaches to the highest occupied molecular orbital for compositions around 50%-50%. In particular, our calculations suggest an increase in the adsorption energy of CO and NO on Pt7Cu6 in comparison with Pt13 and Cu13 unary clusters. Thus, these results form a basis to understand the formation of greater particles as well as to investigate more complex and realistic systems, such as chemical reactions of molecular systems adsorbed on ligand stabilized or supported TM clusters.
Jacobson, Leif David. "Approximating Many-Body Induction to Efficiently Describe Molecular Liquids and Clusters With Improved Accuracy." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1312480919.
Повний текст джерелаMoreira, Emanuel Melo Isaac. "O efeito da correlação eletrônica em clusters de Boro aromáticos: um estudo via Monte Carlo quântico." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/5096.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
In this work we used a combination of density functional theory and quantum Monte Carlo methods to study the effect of electron correlation on stability and aromaticity of anionic Boron clusters (B− 3 and B− 4 ). We found that, in general, the cyclic isomer is energetically more stable than its open linear counterpart. Based on principles of minimum energy and electrophilicity, and maximum hardness, diffusion Monte Carlo indicates that B− 3 cluster is aromatic, however, the results are not conclusive with respect to the B− 4 cluster. Calculations were also performed within the Hartree–Fock approximation. From the obtained results, we analysed the impact of the electron correlation effects in these clusters and found that the correlation of the electrons contributes significantly to the ionization potential and electron affinities varying between 31% and 66% of their total values.
Neste trabalho combinamos a teoria do funcional da densidade com o método de Monte Carlo quântico para estudar o efeito da correlação eletrônica na estabilidade e na aromaticidade de clusters de boro aniônicos (B− 3 e B− 4 ). Verificamos que, em geral, o isômero cíclico é energeticamente mais estável que sua respectiva estrutura linear. Com base no princípio da mínima energia e eletrofilicidade, e máxima dureza, o método Monte Carlo por difusão indicou que o cluster B− 3 é aromático, porém, os resultados para o cluster B− 4 ainda não são conclusivos. Realizamos também cálculos com a aproximação de Hartree-Fock. Dos resultados obtidos, analisamos o impacto do efeito da correlação nesses clusters e verificamos que a correlação dos elétrons contribuem significativamente para o potencial
Gebretsadik, Adane Samuel Gebretsadik. "INTERPLAY BETWEEN CHEMICAL AND MAGNETIC DISORDER IN SELECTED ALLOYS CLOSE TO A FERROMAGNETIC QUANTUM PHASE TRANSITION." Kent State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=kent1527609152939816.
Повний текст джерелаDamasceno, Junior Jose Higino. "Propriedades eletrônicas e estruturais de clusters metálicos via métodos ab initio." Universidade Federal de Goiás, 2015. http://repositorio.bc.ufg.br/tede/handle/tede/4846.
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Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG
Clusters systems are very different from molecules or their bulk materials, since they exhibit many specific properties. As example, the bond in metallic clusters of metallic atoms is intermediate between metallic and covalent bonding. In general, the structural and electronic properties of these systems are very difficult to measure experimentally, and therefore theoretical modeling is very important in characterizing them. In this thesis, we employed ab initio methods to study metallic clusters such as the aluminum hydride clusters as well as a few aromatic metal clusters. The optimized geometries of the studied clusters have been determined using DFT. The electronic structures of these systems were investigated using the QMC methods. The calculations were carried out within the Variational (VMC) and fixed-node diffusion (DMC) quantum Monte Carlo methods. The calculations are also performed in the Hartree-Fock (HF) approximation in order to analyze the impact of electron correlation. With regards the aluminum hydride clusters, the total atomic binding energy impact varies from ~20% up to about ~50%, whereas for the electron binding energy it ranges from ~1% up to ~73%. The decomposition of the electron binding energies clearly shows that both charge redistribution and electron correlation are important in determining the detachment energies, whereas electrostatic and exchange interactions are responsible for the ionization potential. For the aromatic metal clusters, the presence of a dopant plays important role in their electronic properties enhancing their binding energy, electron affinity, hardness and resonance energy.
Clusters são sistemas bastante diferentes de moléculas e sólidos, pois exibem propriedades bastante peculiares. Por exemplo, a ligação em um cluster metálico tem intensidade intermediária entre as ligações covalentes e metálicas. Em geral, as propriedades eletrônicas e estruturais desses sistemas são bastante difíceis de serem medidas experimentalmente e, portanto, uma modelagem teórica é muito importante na caracterização desses. Nesta Tese, utilizamos métodos ab initio para estudar clusters metálicos, tal como clusters de hidretos de alumínio assim como também alguns clusters metálicos aromáticos. As estruturas geométricas dos clusters estudados foram otimizadas via DFT. A estrutura eletrônica desses clusters foi investigada usando o método de Monte Carlo Quântico Variacional (MCQD) e de difusão (MCQD) com aproximação de nós fixos. Os cálculos também foram realizados a partir da aproximação de Hartree-Fock, afim de se analisar o impacto da energia de correlação eletrônica. Para os hidretos de alumínio, a energia de correlação eletrônica tem impacto na energia total de ligação variando de 20% a 50%. Da mesma maneira, a energia de ligação de um elétron ao cluster tem grande contribuição da energia de correlação eletrônica, variando de 1% a 73%. A decomposição da energia de ligação mostra claramente que a relaxação e a correlação eletrônica são importantes na determinação da afinidade eletrônica, enquanto que a interação de troca eletrostática é responsável pelo potencial de ionização. Para os clusters aromáticos, a presença do dopante desempenha um importante papel nas propriedades desses clusters, uma vez que otimiza a energia de ligação, a afinidade eletrônica, a dureza e a energia de ressonância.
Qi, Luo [Verfasser], Maria [Akademischer Betreuer] Chekhova, Maria [Gutachter] Chekhova, and Joachim von [Gutachter] Zanthier. "Non-classical multi-photon light from clusters of colloidal quantum dots / Luo Qi ; Gutachter: Maria Chekhova, Joachim von Zanthier ; Betreuer: Maria Chekhova." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2019. http://d-nb.info/1180028422/34.
Повний текст джерелаPrabha, FNU Sweta. "Theoretical Studies of the Structure and Stability of Metal Chalcogenide CrnTem (1≤n≤6, 1≤m≤8) clusters." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5774.
Повний текст джерелаJantke, Laura-Alice [Verfasser]. "From Zintl Phases to Novel Tetrel Allotropes - Quantum Chemical Considerations of Zintl Phases and Zintl Clusters lead to Novel Tetrel Modifications / Laura-Alice Jantke." München : Verlag Dr. Hut, 2018. http://d-nb.info/1149579161/34.
Повний текст джерелаXu, Liang. "Simulating electronic-structure properties of atomic clusters by Ab-initio calculations, and inter-nuclear quantum-statistical effects of molecules from an integration-free path-integral method /Xu Liang." HKBU Institutional Repository, 2016. https://repository.hkbu.edu.hk/etd_oa/344.
Повний текст джерелаPoblotzki, Anja. "Intermolecular energy scales based on aromatic ethers and alcohols." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2019. http://hdl.handle.net/21.11130/00-1735-0000-0003-C1AD-0.
Повний текст джерелаRupel, Dylan, and Dylan Rupel. "Quantum Cluster Characters." Thesis, University of Oregon, 2012. http://hdl.handle.net/1794/12400.
Повний текст джерелаLópez, José G. "Theoretical studies of the dynamics and spectroscopy of weakly bound systems." The Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=osu1127220592.
Повний текст джерелаNicolas, David. "étude d'agrégats d'oxydes de terres rares." Phd thesis, Université Claude Bernard - Lyon I, 2007. http://tel.archives-ouvertes.fr/tel-00170447.
Повний текст джерелаMedel, Robert. "Schwingungsspektroskopische Untersuchungen zur Chiralitätserkennung und Torsionsdynamik bei Alkoholen." Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-14BC-1.
Повний текст джерелаBittmann, Léa. "Quantum Grothendieck rings, cluster algebras and quantum affine category O." Thesis, Sorbonne Paris Cité, 2019. http://www.theses.fr/2019USPCC024.
Повний текст джерелаThe aim of this thesis is to construct and study some quantum Grothendieck ring structure for the category O of representations of the Borel subalgebra Uq(^b) of a quantum affine algebra Uq(^g). First of all, we focus on the construction of asymptotical standard modules, analogs in the context of the category O of the standard modules in the category of finite-dimensional Uq(^g)-modules. A construction of these modules is given in the case where the underlying simple Lie algebra g is sl2. Next, we define a new quantum torus, which extends the quantum torus containing the quantum Grothendieck ring of the category of finite-dimensional modules. In order todo this, we use notions linked to quantum cluster algebras. In the same spirit, we build a quantum cluster algebra structure on the quantum Grothendieck ring of a monoidal subcategory CZ of the category of finite-dimensional representations. With this quantum torus, we de_ne the quantum Grothendieck ring Kt(O+Z) of a subcategory O+Z of the category O as a quantum cluster algebra. Then, we prove that this quantum Grothendieck ring contains that of the category of finite-dimensional representation. This result is first shown directly in type A, and then in all simply-laced types using the quantum cluster algebra structure of Kt(CZ). Finally, we define (q,t)-characters for some remarkable infinite-dimensional simple representations in the category O+Z. This enables us to write t-deformed analogs of important relations in the classical Grothendieck ring of the category O, which are related to the corresponding quantum integrable systems
Hajdusek, Michal. "Thermodynamics, quantum computation and cluster states." Thesis, University of Leeds, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.531532.
Повний текст джерелаRaussendorf, Robert. "Measurement-based quantum computation with cluster states." Diss., lmu, 2003. http://nbn-resolving.de/urn:nbn:de:bvb:19-13674.
Повний текст джерелаLiao, Rongzhen. "Quantum Chemical Cluster Modeling of Enzymatic Reactions." Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-43026.
Повний текст джерелаJoo, Jaewoo. "Atomic and Optical Realizations of Cluster Quantum Computation." Thesis, Imperial College London, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484425.
Повний текст джерелаBeard, Bernard Borodel. "Improvements in cluster algorithms for quantum spin systems." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38414.
Повний текст джерелаFish, C. D. "Connected quantized Weyl algebras and quantum cluster algebras." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/16636/.
Повний текст джерелаFujii, Keisuke. "Fault-Tolerant Quantum Computation on Logical Cluster States." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/142173.
Повний текст джерела