The interaction of a solitary wave solution with phonons in a one-dimensional model for displacive structural phase transitions

The model of a one-dimensional chain of harmonically coupled particles in local double-well potentials is investigated analytically in the displacive regime. A perturbation treatment of the interaction of a kink (wall separating ordered clusters) with extended states (optical phonons modified by the kink) is given. It is shown that amplitude fluctuations of the phonons lead to displacements of the kink in the direction of higher phonon amplitudes. These results are tested numerically by a molecular dynamics technique. The latter method is also applied to investigate the effect of an energy flux along the chain on the kink. The result is a movement of the kink in the direction opposite to the energy flux.