Session LC42 - Phase Transitions and Critical Phenomena.
ORAL session, Tuesday afternoon, March 23
Knollwood Room A, Omni Hotel
We use spin-dynamics techniques to perform large-scale simulations of the dynamic behavior of the classical Heisenberg antiferromagnet in three dimensions. Time-evolutions of spin configurations are determined numerically from coupled equations of motion for individual spins using a new algorithm(M. Krech, Alex Bunker, D. P. Landau, Computer Phys. Comm. 111), 1 (1998) based on Suzuki-Trotter decompositions of exponential operators. The dynamic structure factor is calculated from the space- and time-displaced spin-spin correlation function. We study the width of spin-wave peaks as a function of the wave-vector for temperature below but close to the critical value. Our results are compared with some theoretical predictions which in turn disagree with very recent experimental results. Our preliminary data indicate that hydrodynamic theory only holds for wave-vectors which are far from the Brillouin zone boundary.