The effect of discrete breathers on heat conduction in nonlinear chains

TL;DR

This paper investigates how discrete breathers influence heat conduction in nonlinear chains, revealing that their interactions with phonons cause the heat transport properties to depend on the ratio of next-nearest to nearest neighbor couplings.

Contribution

It demonstrates that discrete breathers significantly affect heat conduction in nonlinear lattices, challenging the notion of universal heat conduction exponents.

Findings

Heat conduction exponent $eta$ depends on coupling ratio $\gamma$.

Discrete breathers interact with phonons affecting heat transport.

Nonlinear excitations influence thermal conductivity in nonlinear chains.

Abstract

Intensive studies in the past decades have suggested that the heat conductivity $\kappa$ diverges with the system size $L$ as $\kappa\sim L^{\alpha}$ in one dimensional momentum conserving nonlinear lattices and the value of $\alpha$ is universal. But in the Fermi-Pasta-Ulam-$\beta$ lattices with next-nearest-neighbor interactions we find that $\alpha$ strongly depends on $\gamma$, the ratio of the next-nearest-neighbor coupling to the nearest-neighbor coupling. We relate the $\gamma$-dependent heat conduction to the interactions between the long-wavelength phonons and the randomly distributed discrete breathers. Our results provide an evidence to show that the nonlinear excitations affect the heat transport.