Raphael Lefevere Alain Schenkel Perturbative analysis of anharmonic chains of oscillators out of equilibrium. (334K, ps) ABSTRACT. We compute the first-order correction to the correlation functions of the stationary state of a stochastically forced harmonic chain out of equilibrium when a small on-site anharmonic potential is added. This is achieved by deriving a suitable formula for the covariance matrix of the invariant state. We find that the first-order correction of the heat current does not depend on the size of the system. Second, the temperature profile is linear when the harmonic part of the on-site potential is zero. The sign of the gradient of the profile is, however, opposite to the sign of the temperature difference of the heat baths.