The effect of discrete breathers on heat conduction in nonlinear chains

Abstract

Intensive studies in the past decades have suggested that the heat conductivity $κ$ diverges with the system size $L$ as $κ\sim L^α$ in one dimensional momentum conserving nonlinear lattices and the value of $α$ is universal. But in the Fermi-Pasta-Ulam-$β$ lattices with next-nearest-neighbor interactions we find that $α$ strongly depends on $γ$, the ratio of the next-nearest-neighbor coupling to the nearest-neighbor coupling. We relate the $γ$-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.

4 pages, 5 figures