Comparison between continued-fraction and computer-simulation methods applied to a classical Heisenberg chain

A detailed comparison between the simulation data of Heller and Blume, and various continued-fraction expansions, is presented. It is shown that the three-pole expansion is qualitatively wrong while four- and six-pole expansions are in good agreement with the simulation data. A possibility of using continued-fraction representations to interpret simulation results is discussed. The convergence of the various approximations in the frequency domain is investigated.