A direct calculation of the free energy from the Bethe ansatz equation for the Heisenberg model
نویسندگان
چکیده
A direct calculation of the free energy from the Bethe ansatz equation for the Heisenberg model. Abstract Thermodynamics of the XXX Heisenberg model is studied. The trace of the Boltz-mann weight with respect to the Hilbert space is taken in the thermodynamic limit with the number of up-spins being fixed. The expression of the trace gives an explanation why the correct thermodynamic quantities are derived from the string hypothesis. Combining this with the previous result, we conclude that the free energy can be calculated only by assuming the Bethe ansatz equation. The method is more direct than other known methods which were used to derive the free energy.
منابع مشابه
Direct Calculation of Thermodynamic Quantities for
The XXX Heisenberg model is studied at finite temperature. The free energy is derived without recourse to Thermal Bethe Ansatz method and Quantum Transfer Matrix method. The result perfectly agrees with the free energy derived by Thermal Bethe Ansatz method. An explicit expression of the cluster expansion coefficient in arbitrary order is presented for the first time.
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