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Fully-Factorized Ground-State in Frustrated Spin Hamiltonian

Ghasimakbari, Taher | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41404 (04)
  4. University: Sharif University of Technology
  5. Department: Physics
  6. Advisor(s): Langari, Abdollah
  7. Abstract:
  8. Except of few cases the exact, analytic forms of most applicable many-body Hamiltonian ground-states are unknown. Our knowledge in most cases come through computer-based simulations. In recent years a well-structured method has been developed to derive an analytic form for spin Hamiltonian ground-states. ?is method through whi? an analytical fully-factorized ground-state can be derived for many-spin Hamiltonians is independent of the model structure and has unique procedure for any spin Hamiltonian. ?e fully-factorized ground state whi? has been developed, minimizes the energy of the Hamiltonian by minimizing ea? pair-interaction in the Hamiltonian. However, this approval can not be fulfilled in frustrated spin models. Although, pair Hamiltonians in a frustrated spin Hamiltonian are not all in their ground-state, the whole system could se?le in a collective ground-state. Few methods have been utilized to find circumstances under whi? the frustrated spin Hamiltonian could find a fully-factorized ground-state. In a recent work the exact fully-factorized ground state for a Heisenberg Hamiltonian with next-nearest neighbor interaction has been introduced for 1 2 . ?e approa? is limited for small s models. We have addressed the validity regime of coupling constants -in the frustrated Heisenberg ?ain- where the fully-factorized state is a ground state. the approa? is based on Rayleigh–S?rodinger perturbation theory and spin-wave expansion. the main goal of our approa? is its validity for any value of spin, specially large spins
  9. Keywords:
  10. Spin Wave Theory ; Full-Factorized State ; Frustration ; Rayleigh-Shrodinger Perturbation Theory

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