The time dependence of the energy fluctuations in a classical Heisenberg chain is studied. The exact low-temperature limit is determined, and the time dependence is given by $J_0\left(4\mathrm{}sin\right(\frac{1}{2}q\left)t\right)$. At nonzero temperatures approximate results are obtained by means of the continued-fraction method. Analytic expressions for the second and fourth frequency moments are given.

• Received 26 October 1979

DOI:https://doi.org/10.1103/PhysRevB.21.4108