KINK DYNAMICS IN THE PERIODICALLY MODULATED PHI(4) MODEL

Kink dynamics in the spatially modulated phi4 model is studied analyti cally with the Born approximation and a collective-coordinate approach , and numerically. Four types of kink behavior can be distinguished: ( i) radiation at high velocity, (ii) strong resonant beating in the kin k velocity, (iii) propagation of the kink with almost periodic velocit y oscillations, and (iv) trapping at low velocity. Although some of th ese regimes exist also in the sine-Gordon (SG) case, the phi4 model ex hibits a much richer dynamics due to the existence of a localized inte rnal mode of the kink, which can exchange energy with the translationa l mode. The propagation in a modulated substrate is very sensitive to this effect, and in this respect the phi4 model could be more represen tative of real systems which may not have the peculiar properties of t he integrable SG model.