Solitons in crystalline polyethylene: Isolated chains in the transconformation

This paper is devoted to the investigation of soliton-type excitations in crystalline polyethylene. A numerical solution of the problem of the existence and stability of dynamical solitons in an isolated polyethylene chain has been obtained. In the framework of a realistic model, taking into account deformations of the valence angles and valence bonds, soliton-type excitations describing propagation of the local region of tension along the chain have been found. The existence of the solitons of tension is a direct consequence of a predominance of geometric nonlinearity in a transzigzag chain over a physical one. It is shown that the polyethylene molecule has a comparitively narrow spectrum of soliton velocities in the supersonic region. The modeling performed shows that the solitons of tension are stable over the whole area of their existence. The region of parameters, where interaction between solitons is elastic, has been found. In our numerical analysis we took a refined version of an analytic solution for the limiting case of rigid bonds as the starting point.