Energy transport in anharmonic lattices close and far from equilibrium

TL;DR

This paper investigates heat transport in the Fermi-Pasta-Ulam chain, demonstrating diverging conductivity in large systems and validating fluctuation conjectures through numerical simulations with thermostats.

Contribution

It provides numerical evidence of diverging thermal conductivity and confirms fluctuation relations in anharmonic lattices near and far from equilibrium.

Findings

Conductivity diverges in the thermodynamic limit.

Heat current fluctuations agree with Gallavotti-Cohen conjectures.

Simulations with thermostats reveal behavior across temperature gradients.

Abstract

The problem of stationary heat transport in the Fermi-Pasta-Ulam chain is numerically studied showing that the conductivity diverges in the thermodynamic limit. Simulations were performed with time-reversible thermostats, both for small and large temperature gradients. In the latter case, fluctuations of the heat current are shown to be in agreement with the recent conjectures of Gallavotti and Cohen.