Multispin correlations in the Ising model

Abstract

The multiparticle entropy method, as developed by the theory of atomic ordering in multicomponent solid solutions, is now applied to solving the problem of a system with magnetic interactions of Ising's type with an arbitrary spin. The internal energy of the magnetic system is calculated using a diagram technique, introduced by analogy with the higher-temperature expansion. A considerable extension of the applicability range of the method towards the lower temperatures is achieved by renormalizing the effective interaction potentials. The number of exchange constants, as well as their sign are arbitrary. The method applies to any type of crystalline structure.