paper

Long-range interacting rotators: connection with the mean--field approximation

arXiv:cond-mat/9911030 · doi:10.1103/PhysRevLett.84.208

Abstract

We analyze the equilibrium properties of a chain of ferromagnetically coupled rotators which interact through a force that decays as where r is the interparticle distance and . Our model contains as particular cases the mean field limit () and the first-neighbor model (). By integrating the equations of motion we obtain the microcanonical time averages of both the magnetization and the kinetic energy. Concerning the long-range order, we detect three different regimes at low energies, depending on whether belongs to the intervals , or . Moreover, for , the microcanonical averages agree, after a simple scaling, with those obtained in the canonical ensemble for the mean-field XY model. This correspondence offers a mathematically tractable and computationally economic way of dealing with systems governed by slowly decaying long-range interactions.

4 pages, 4 figures, to appear in Phys. Rev. Lett

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