FAST SPIN DYNAMICS ALGORITHMS FOR CLASSICAL SPIN SYSTEMS

We have proposed new algorithms for the numerical integration of the e quations of motion for classical spin systems. In close analogy to sym plectic integrators for Hamiltonian equations of motion used in Molecu lar Dynamics, these algorithms are based on the Suzuki-Trotter decompo sition of exponential operators and unlike more commonly used algorith ms exactly conserve spin length and, in special cases, energy. Using h igher order decompositions we investigate integration schemes of up to fourth order and compare them to a well-established fourth order pred ictor-corrector method. We demonstrate that these methods can be used with much larger time steps than the predictor-corrector method and th us may lead to a substantial speedup of computer simulations of the dy namical behavior of magnetic materials. (C) 1998 Elsevier Science B.V.