Browsing by Subject "Sistemas de férmions"
Now showing items 1-10 of 10
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Ansatz de Bethe e princípio variacional aplicados a sistemas de poucas partículas interagentes em um potencial harmônico unidimensional
(2014) [Thesis]Neste trabalho nós desenvolvemos uma abordagem baseada no método do ansatz de Bethe e no princípio variacional para encontrar a energia do estado fundamental para sistemas unidimensionais formados por um número pequeno de ... -
Campo magnético crítico superior de um supercondutor impuro
(1988) [Dissertation]O campo magnético crítico superior e a temperatura crítica são calculadas para supercondutores com impurezas. Na avaliação das funções de Green do problema são usadas as autofunções exatas de um elétron em um campo magnético ... -
From the atomic limit to a metal-insulator transition in the hubbard model
(1995) [Journal article]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 ... -
Modelos exatamente solúveis para gases ultrafrios
(2012) [Thesis]Modelos exatamente solúveis para gases de férmions e bósons ultrafrios são estudados via o método do ansatz de Bethe termodinâmico. Resultados analíticos e numéricos são obtidos para o gás de Fermi de duas componentes com ... -
Phase diagrams of three-component attractive ultracold fermions in one dimension
(2012) [Journal article]We investigate trions, paired states and quantum phase transitions in one-dimensional SU(3) attractive fermions in external fields by means of the Bethe ansatz formalism. Analytical results for the ground state energy, ... -
Replica symmetry breaking in the transverse-field Ising spin-glass model : two fermionic representations
(2005) [Journal article]We analyze the infinite range Ising spin glass in a transverse-field below the critical temperature by a one step replica symmetry breaking theory. The set of n replicas is divided in r blocks of m replicas each. We present ... -
Simple approximation for the bethe ansatz solution of the one-dimensional fermi gas
(1987) [Journal article]We present a simple approximation scheme for the solution of the integral equations resulting from the Bethe-ansatz diagonalization of the one-dimensional Fermi gas with ô-function attraction. These equations arise for the ... -
Tight-binding treatment of the Hubband model in infinite dimensions
(1996) [Journal article]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 ... -
Trace of broken integrability in stationary correlation properties
(2014) [Journal article]We show that the breaking of integrability in the fundamental one-dimensional model of bosons with contact interactions has consequences on the stationary correlation properties of the system. We calculate the energies and ... -
Two interacting fermions in a one-dimensional harmonic trap : matching the Bethe ansatz and variational approaches
(2012) [Journal article]In this work, combining the Bethe ansatz approach with the variational principle, we calculate the ground-state energy of the relative motion of a system of two fermions with spin up and spin down interacting via a ...
