Fluctuation-dissipation relation for the Ising-Glauber model with arbitrary exchange couplings

Abstract

We derive an exact expression of the response function to an infinitesimal magnetic field for the Ising-Glauber model with arbitrary exchange couplings.nThe result is expressed in terms of thermodynamic averages and does not depend on initial conditions or dimension of space. The comparison with the equilibrium case gives some understanding on the way the fluctuation-dissipation theorem is violated out-of-equilibrium.