2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/94443Linear theory for phonon scattering by discrete breathers in the discrete nonlinear Schroedinger equation using the transfer matrix approach is presented. Transmission and reflection coefficients are obtained as a function of the wave vector of the input phonon. The occurrence of a nonzero transmission, which in fact becomes perfect for a symmetric breather, is shown to be connected with localized eigenmodes thresholds. In the weak-coupling limit, perfect reflection are shown to exist, which requires two scattering channels. A necessary condition for a system to have a perfect reflection is also considered in a general context.13 pages 11 figures in EPS, RevTeX, Phys. Rev. E acceptedExactly Solvable and Integrable SystemsDisordered Systems and Neural NetworksQuantum Physicstext