Exact diagonalization studies of a one-dimensional system at electron density rho=0.4: effect of the Coulomb repulsions and distant transfer

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Title: Exact diagonalization studies of a one-dimensional system at electron density rho=0.4: effect of the Coulomb repulsions and distant transfer
Authors: Ouchni, Fatiha
Thesis advisor: Apl. Prof. Dr. Juergen Schnack
Thesis referee: Apl. Prof. Dr. Klaus Betzler
Abstract: An extended Hubbard model with large short and long-ranged Coulomb repulsions and distant transfer is numerically investigated by use of the Lanczos exact diagonalization (ED) method to study the charge order and unconditional dimerization of a chain at density rho (ρ)= 0.4. From the analysis of the spin and charge correlation functions, a picture consistent with the formation of a dimer insulating state, which is of Wigner lattice-type (WL) charge order (CO), is obtained. The next-nearest neighbour (NNN) hopping t2 enhances the intradimer correlations and weakens the interdimer correlations. Implications for the CuO2 chains in Sr14Cu24O41 are discussed.We have also introduced a Heisenberg model which parametrically depends on hole positions. If the electrostatic hole-hole repulsion is included such a model allows to evaluate all energy eigenvalues and eigenstates (for small system size) and thus enables us to evaluate thermodynamic properties as function of temperature,magnetic field, and doping. Assuming certain exchange constants we can investigate the influence of the electrostatic hole-hole repulsion on ground state properties as well as on thermal averages like the magnetization which include contributions of low-lying spin-hole configurations.
URL: https://repositorium.ub.uni-osnabrueck.de/handle/urn:nbn:de:gbv:700-2006092719
Subject Keywords: Exact diagonalization; extended hubbard model; Coulomb repulsion; distant transfer; charge order; dimerization; Heisenberg model; magnetization
Issue Date: 25-Sep-2006
Type of publication: Dissertation oder Habilitation [doctoralThesis]
Appears in Collections:FB04 - E-Dissertationen

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