Alex Bunker

Fast spin dynamics algorithms for classical spin systems

We have proposed new algorithms for the numerical integration of the equations of motion for classical spin systems. In close analogy to symplectic integrators for Hamiltonian equations of motion used in Molecular Dynamics these algorithms are based on the Suzuki-Trotter decomposition of exponential operators and unlike more commonly used algorithms exactly conserve spin length and, in special cases, energy. Using higher order decompositions we investigate integration schemes of up to fourth order and compare them to a well established fourth order predictor-corrector method. We demonstrate that these methods can be used with much larger time steps than the predictor-corrector method and thus may lead to a substantial speedup of computer simulations of the dynamical behavior of magnetic materials.

Spin-dynamics simulations of the magnetic dynamics ofRbMnF3and direct comparison with experiment

Spin-dynamics techniques have been used to perform large-scale simulations of the dynamic behavior of the classical Heisenberg antiferromagnet in simple cubic lattices with linear sizes

Dynamic critical behavior of the classical anisotropic BCC Heisenberg antiferromagnet

L\leq 60

Critical dynamics of the bcc classical Heisenberg magnets

. This system is widely recognized as an appropriate model for the magnetic properties of RbMnF

Critical dynamics of the anisotropic BCC Heisenberg antiferromagnet

_3

Magnetic excitations and critical dynamics in RbMnF3: simulation versus theory and experiment

. Time-evolutions of spin configurations were determined numerically from coupled equations of motion for individual spins using a new algorithm implemented by Krech {\it etal}, which is based on fourth-order Suzuki-Trotter decompositions of exponential operators. The dynamic structure factor was calculated from the space- and time-displaced spin-spin correlation function. The crossover from hydrodynamic to critical behavior of the dispersion curve and spin-wave half-width was studied as the temperature was increased towards the critical temperature. The dynamic critical exponent was estimated to be

Spin dynamics study of the critical dynamics of the anisotropic three-dimensional Heisenberg antiferromagnet (abstract)

z=(1.43\pm 0.03)

DISSOCIATION AND THERMODYNAMICS OF DENSE FLUID HYDROGEN

, which is slightly lower than the dynamic scaling prediction, but in good agreement with a recent experimental value. Direct, quantitative comparisons of both the dispersion curve and the lineshapes obtained from our simulations with very recent experimental results for RbMnF

Critical dynamics of the body-centered-cubic classical Heisenberg antiferromagnet.

_3

Classical ferromagnet with double-exchange interaction: High-resolution Monte Carlo simulations

are presented.