Summary
By starting from the formal expansion of the matrix elements ofz=exp [x+λy] in powers of thec-number λ, a general algorithm is derived, for the expansion of the partition function of a lattice system with nearest-neighbour interaction. This is applied to the calculation of the free energy of a spin-1/2 Hamiltonian up to the fourth perturbative order.
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References
T. Matsubara:Prog. Theor. Phys.,14, 351 (1955);F. J. Dyson:Phys. Rev.,102, 1217, 1230 (1956).
See for exampleR. P. Feynman:Statistical Mechanics, a Set of Lectures (W. A. Benjamin, Inc., New York, N. Y., Amsterdam, 1972), p. 66.
C. Buzano, M. Rasetti andM. Vadacchino:Prog. Theor. Phys.,68, 703, 716 (1982).
A. Riccardi:Lett. Nuovo Cimento,40, 147 (1984).
C. Domb andM. S. Green:Phase Transition and Critical Phenomena, Vol. 3 (Academic Press, London, New York, N.Y, San Francisco, Cal, 1974), Chapt. 1.
N. L. Biggs andA. T. White:Permutation Groups and Combinatorial Structures (Cambridge University Press, London, New York, N.Y., Melbourne, 1979), Chapt. 5.
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Riccardi, A. A new perturbative approach to the study of quantum systems at finite temperature. Nuov Cim B 105, 525–572 (1990). https://doi.org/10.1007/BF02722884
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DOI: https://doi.org/10.1007/BF02722884