Il Nuovo Cimento B (1971-1996)

, Volume 105, Issue 5, pp 525–572 | Cite as

A new perturbative approach to the study of quantum systems at finite temperature

  • A. Riccardi


By starting from the formal expansion of the matrix elements ofz=exp [xy] 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.


PACS 02.10.Gd Order lattices and ordered algebraic structures PACS 05.30.Ch Quantum ensemble theory 


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Copyright information

© Società Italiana di Fisica 1990

Authors and Affiliations

  • A. Riccardi
    • 1
  1. 1.Dipartimento di Fisica del PolitecnicoTorinoItalia

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