Temperature-dependent fourth moment of the relaxation function for cubic Heisenberg paramagnets

Useful expressions, solely in terms of appropriate lattice Green functions, are derived for the fourth moment of the relaxation function of a Heisenberg paramagnet having cubic symmetry (s.c., b.c.c. and f.c.c.) and nearest-neighbour exchange interactions. As is customary, the temperature dependence was estimated on the basis of the spherical model and with a simple random-phase type decoupling of the four-spin correlation functions.