Discrete breathers assist energy transfer to ac driven nonlinear chains

TL;DR

This study investigates how discrete breathers facilitate energy transfer in nonlinear chains driven by an external AC source, revealing the role of nonlinearity type and breather dynamics in energy transfer efficiency.

Contribution

It demonstrates that moving discrete breathers can significantly enhance energy transfer in nonlinear chains under AC driving, depending on the nonlinearity type and driving frequency.

Findings

Energy transfer depends on nonlinearity type and driving frequency.

Moving discrete breathers are key to efficient energy transfer.

Hard and soft nonlinearities support different breather behaviors.

Abstract

One-dimensional chain of pointwise particles harmonically coupled with nearest neighbors and placed in six-order polynomial on-site potentials is considered. Power of the energy source in the form of single ac driven particles is calculated numerically for different amplitudes $A$ and frequencies $\omega$ within the linear phonon band. The results for the on-site potentials with hard and soft nonlinearity types are compared. For the hard-type nonlinearity, it is shown that when the driving frequency is close to (far from) the {\em upper} edge of the phonon band, the power of the energy source normalized to $A^2$ increases (decreases) with increasing $A$. In contrast, for the soft-type nonlinearity, the normalized power of the energy source increases (decreases) with increasing $A$ when the driving frequency is close to (far from) the {\em lower} edge of the phonon band. Our further demonstrations indicate that, in the case of hard (soft) anharmonicity, the chain can support movable discrete breathers (DBs) with frequencies above (below) the phonon band. It is the energy source quasi-periodically emitting moving DBs in the regime with driving frequency close to the DBs frequency, that induces the increase of the power. Therefore, our results here support the mechanism that the moving DBs can assist energy transfer from the ac driven particle to the chain.