Spin correlations in a classical Heisenberg paramagnet

A computer model of a Heisenberg paramagnet is constructed from a thousand classical spin vectors situated on a simple cubic lattice and interacting through nearest-neighbour exchange forces. The motion of an initial random set of spins is calculated explicitly and used to evaluate the correlations as a function of time for various neighbours. The neutron scattering from a polycrystalline paramagnet is predicted from the correlations and compared with experimental data on RbMnF3.