Moving discrete breathers in a $\beta$-FPU lattice revisited

TL;DR

This paper revisits moving discrete breathers in a $eta$-FPU lattice, introducing a numerical method for their construction, analyzing their stability through Floquet analysis, and exploring their dynamical behavior and bifurcations.

Contribution

It presents a systematic numerical procedure for constructing moving breathers over multiple lattice sites and analyzes their stability and dynamics in the $eta$-FPU lattice.

Findings

Existence of moving breathers over multiple sites per period.

Identification of multivalued energy-frequency relationships.

Observation of breather slowing down due to instabilities.

Abstract

In the present work we revisit the existence, stability and dynamical properties of moving discrete breathers in $\beta$-FPU lattices. On the existence side, we propose a numerical procedure, based on a continuation along a sequence of velocities, that allows to systematically construct breathers traveling more than one lattice site per period. On the stability side, we explore the stability spectrum of the obtained waveforms via Floquet analysis and connect it to the energy-frequency bifurcation diagrams. We illustrate in this context examples of the energy being a multivalued function of the frequency, showcasing the coexistence of different moving breathers at the same frequency. Finally, we probe the moving breather dynamics and observe how the associated instabilities change their speed, typically slowing them down over longtime simulations.