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Finite Temperature Many-Body Theory with the Lipkin Model

S. Y. Tsay Tzeng·P. J. Ellis·T. T. S. Kuo·E. Osnes
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Abstract

We have compared exact numerical results for the Lipkin model at finite temperature with Hartree-Fock theory and with the results of including in addition the ring diagrams. In the simplest version of the Lipkin model the Hartree-Fock approach shows a ``phase transition" which is absent in the exact results. For more realistic cases, Hartree-Fock provides a very good approximation and a modest improvement is obtained by adding the ring diagrams.

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S. Y. Tsay Tzeng, P. J. Ellis, T. T. S. Kuo, E. Osnes. 1993-08-02. Finite Temperature Many-Body Theory with the Lipkin Model. https://doi.org/10.1016/0375-9474(94)90774-9

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