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Exact time correlation functions for N classical Heisenberg spins in the `squashed' equivalent neighbor model

Marco Ameduri·Richard A. Klemm
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Abstract

We present exact integral representations of the time-dependent spin-spin correlation functions for the classical Heisenberg N-spin `squashed' equivalent neighbor model, in which one spin is coupled via the Heisenberg exchange interaction with strength $J_1$ to the other N-1 spins, each of which is coupled via the Heisenberg exchange coupling with strength $J_2$ to the remaining N-2 spins. At low temperature T we find that the N spins oscillate in four modes, one of which is a central peak for a semi-infinite range of the values of the exchange coupling ratio. For the N=4 case of four spins on a squashed tetrahedron, detailed numerical evaluations of these results are presented. As $T\to\infty$, we calculate exactly the long-time asymptotic behavior of the correlation functions for arbitrary N, and compare our results with those obtained for three spins on an isosceles triangle.

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Marco Ameduri, Richard A. Klemm. 2003-02-01. Exact time correlation functions for N classical Heisenberg spins in the `squashed' equivalent neighbor model. https://doi.org/10.1088/0305-4470/37/4/001

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