Computer experiments on the dilute three-dimensional Heisenberg magnet: Infinite temperature

We have used computer simulations to study the dynamic behavior at infinite temperature of a threedimensional Heisenberg magnet with impurities. Computation has been done for the case of a simple-cubic lattice (maximum size: 27 × 27 × 27 spins) with nearest-neighbor exchange. The spin self-correlation function as well as the first four near-neighbor correlation functions are obtained for times $t$ out to the order of $\frac{3}{J}$. While it is not clear that these data may be extrapolated to obtain long-time behavior, particularly at low concentration, the self-correlation function appears to fall off less rapidly than the $t^{-\frac{3}{2}}$ law consistent with spin diffusion, even at concentrations well above the percolation limit.