Dynamics and thermodynamics of rotators interacting with both long and short range couplings

Alessandro Campa; Andrea Giansanti; David Mukamel; Stefano Ruffo

doi:10.1016/j.physa.2006.01.003

paper

Dynamics and thermodynamics of rotators interacting with both long and short range couplings

arXiv:cond-mat/0510508 · doi:10.1016/j.physa.2006.01.003

Abstract

The effect of nearest-neighbor coupling on the thermodynamic and dynamical properties of the ferromagnetic Hamiltonian Mean Field model (HMF) is studied. For a range of antiferromagnetic nearest-neighbor coupling, a canonical first order transition is observed, and the canonical and microcanonical ensembles are non-equivalent. In studying the relaxation time of non-equilibrium states it is found that as in the HMF model, a class of non-magnetic states is quasi-stationary, with an algebraic divergence of their lifetime with the number of degrees of freedom $N$ . The lifetime of metastable states is found to increase exponentially with $N$ as expected.

12 pages, 6 figures