  We numerically analyze the interaction of small-amplitude phonon waves with
standing gap discrete breather (DB) in strained graphene. To make the system
support gap DB, strain is applied to create a gap in the phonon spectrum. We
only focus on the in-plane phonons and DB, so the issue is investigated under a
quasi-one-dimensional setup. It is found that, for the longitudinal sound waves
having frequencies below 6 THz, DB is transparent and thus no radiation of
energy from DB takes place; whereas for those sound waves with higher
frequencies within the acoustic (optical) phonon band, phonon is mainly
transmitted (reflected) by DB, and concomitantly, DB radiates its energy when
interacting with phonons. The latter case is supported by the fact that, the
sum of the transmitted and reflected phonon energy densities is noticeably
higher than that of the incident wave. Our results here may provide insight
into energy transport in graphene when the spatially localized nonlinear
vibration modes are presented.
