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

TL;DR

This paper derives an exact response function for the Ising-Glauber model with arbitrary couplings, providing insights into fluctuation-dissipation theorem violations out-of-equilibrium.

Contribution

It presents a novel exact expression for the response function in the Ising-Glauber model with arbitrary exchange couplings, independent of initial conditions or spatial dimension.

Findings

Response function expressed in thermodynamic averages.

Clarifies how fluctuation-dissipation theorem is violated out-of-equilibrium.

Applicable to models 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.