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One Dimensional Extended Hubbard Model with Long Range Interactions

Talebi, Amir Hossein | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 48016 (04)
  4. University: Sharif University of Technology
  5. Department: physics
  6. Advisor(s): Davoudi, Bahman; Rahimi Tabar, Mohammad Reza
  7. Abstract:
  8. In this thesis, we have studied the ground state properties of one-dimensional many body electron systems using the extended Hubbard model. Following the important work of Tremblay and Davoudi, we have used the TPSC approach to derive explicit expressions for spin and charge response functions. The response functions are expressed in terms of the free response function χ_0 and local field factors U_cc and U_ss. The local field factors can be written in terms of the pair correlation functions. Also fluctuation-dissipation theorem allows us to write pair correlation functions in terms of the structure factors. In the first part of thesis, we study the ground state properties of the system by detecting the singularities of the response functions. We predict that this system shows different types of ordering, such as charge and spin density wave, incommensurate charge and spin density wave, parmagnetism, phase separation and ferromagnetism. We draw the phase diagram which separates the different phases of the system.In the second part of thesis, we have considered the atoms or molecules as basic particles of the one-dimensional lattice. These particles have electric dipole moment and therefore they interact via dipole-dipole interaction. To investigate the electronic structure of system, we have considered the extended Hubbard model with dipole-dipole potential and calculated charge and spin response functions in the bases of the ETPSC approach
  9. Keywords:
  10. Hubbard Model ; Long Range Interaction ; Two Particle Self-consistent Approach (TPSC) ; Spin-Charge Susceptibility ; Cold Atoms

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