Navegação por Assunto "Modelo de hubbard"
Resultados 1-18 de 18
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Approximate Treatment of a Two-Dimensional Anisotropic Peierls-Hubbard Model
(1993) [Artigo de periódico]A Green-function formalism is presented to study a Peierls-Hubbard Hamiltonian in two dimensions. The 1attice consists of parallel dimerized chains with alternating nearest-neighbor hoppings t and t 11 and another hopping ... -
Dinâmica de bósons de spin 1 em poços múltiplos
(2020) [Tese]Neste trabalho, estudamos a dinâmica de bósons de spin 1 em potenciais de poço duplo ou triplo. Temos por base o modelo de Bose-Hubbard, muito utilizado para o estudo teórico de átomos ultrafrios confinados em potenciais ... -
Efeitos de dopagem e desordem em modelos de sistemas eletrônicos correlacionados
(2014) [Tese]Elétrons em bandas estreitas de energia são fortemente afetados pela interação coulombiana como também por desordem na rede. Ambos os efeitos podem levar à localização, mas de naturezas diferentes: estado isolante de Mott, ... -
Eletronic and phonomic states of the Holstein-Hubbard dimer of variable length
(1998) [Artigo de periódico]We consider a model Hamiltonian for a dimer of length a including all the electronic one- and two-body terms consistent with a single orbital per site, a free Einstein phonon term for a frequency V, and an electronphonon ... -
From the atomic limit to a metal-insulator transition in the hubbard model
(1995) [Artigo de periódico]Starting from the exact solution of the Hubbard model in the atomic limit, and treating the hopping term as a perturbation by means of a diagram technique, we discuss the electronic structure of the model in some simple ... -
Green-Function Method for a Mixed-Valence Hamiltonian
(1984) [Artigo de periódico]A Green-function diagrammatic method is utilized to calculate the occupation number of a narrow (j) band in a mixed-valence system. The method is a generalization of the Hubbard-1 approximation for a two-band Hamiltonian. ... -
Modelo de Hubbard em clusters : interações competitivas e frustração geométrica
(2019) [Tese]Com foco em efeitos de frustração geométrica, realizamos um estudo detalhado de algumas propriedades termodinâmicas do modelo de Hubbard estendido, com interação local (U) e entre vizinhos mais próximos (V ), em clusters ... -
Modelo de Hubbard estendido aplicado ao estudo da supercondutividade em compostos de cobalto
(2006) [Dissertação]Neste trabalho estudamos algumas propriedades supercondutoras de compostos hidratados de cobalto do tipo NaxCoO2 · yH2O. Estes compostos são formados por planos de CoO2, intercalados por planos de íons de Na e moléculas ... -
Nature of insulating state in the three-band hubbard model : a tight-binding approach
(1995) [Artigo de periódico]We study the three-band Hubbard model, commonly used to describe the copper-oxygen planes of high-Tc superconductors, from the point of view of electronic properties. Utilizing perturbation theory around the atomic limit ... -
Propriedades eletrônicas dos fullerenos sólidos C60 e K3C60
(1995) [Resumo publicado em evento] -
Quantum critical behavior and thermodynamics of the repulsive one-dimensional Hubbard model in a magnetic field
(2020) [Artigo de periódico]Even though the Hubbard model is one of the most fundamental models of highly correlated electrons, analytical and numerical data describing its thermodynamics at nonzero magnetization are relatively scarce. We present a ... -
Quantum density anomaly in optically trapped ultracold gases
(2020) [Artigo de periódico]Water, the substance of life, is known for its myriad of anomalous properties, whose origins are still the subject of intense debates. In order to provide a different insight into this problem, we show how its density ... -
Solution of a two-leg spin ladder system
(2000) [Artigo de periódico]A model for a spin-1/2 ladder system with two legs is introduced. It is demonstrated that this model is solvable via the Bethe ansatz method for arbitrary values of the rung coupling J. This is achieved by a suitable mapping ... -
Supercondutividade em fullerenos dopados
(1996) [Resumo publicado em evento] -
Thermodynamic anomalies in ultracold quantum gases
(2021) [Tese]Although well-researched as a prototype Hamiltonian for strongly interacting quantum systems, the Bose-Hubbard model has not so far been explored as a fluid system with waterlike anomalies. Water, the substance of life, ... -
Tight-binding treatment of the Hubband model in infinite dimensions
(1996) [Artigo de periódico]We discuss the infinite dimension limit of the Hubbard model by means of a perturbative expansion of the one-particle Green’s function around the atomic limit. The diagrammatic structure is simplified in this limit, allowing ... -
Transições de fase quânticas e equações do ansatz de Bethe para o modelo de Bose-Hubbard de dois sítios
(2010) [Dissertação]Neste trabalho nós investigamos o modelo de Bose-Hubbard de dois sítios atrativo sob o ponto de vista do ansatz de Bethe. Este modelo descreve o tunelamento Josephson entre dois condensados de Bose-Einstein. Nós iniciamos ... -
Two-site Bose-Hubbard model with nonlinear tunneling : classical and quantum analysis
(2017) [Artigo de periódico]The extended Bose-Hubbard model for a double-well potential with atom-pair tunneling is studied. Starting with a classical analysis we determine the existence of three quantum phases: self-trapping, phase-locking, and ...