Analytical study and computer simulation of discrete optical breathers in a zigzag chain
Résumé
We present analytical and numerical studies of the discrete breathers identified as localized deformations of valence angles and bonds in crystalline polyethylene (PE). It is shown that such breathers can exist both outside and within the optical band and may propagate with subsonic velocities along the polymer chain. The analytical results are confirmed by numerical simulation using the molecular dynamics procedure. We examine also the stability of the breathers relative to thermal excitations and mutual collisions as well as to collisions with the acoustic nontopological and topological solitons. The conditions of the breathers existence depend strongly on their generating frequency, the relationship between the stiffness of valence bonds and valence angles as well as on the type of nonlinear characteristics of intrachain interactions.