Breather in the motion of a polaron in an electric field

It has been known that a charged polaron will reach a constant speed after being accelerated only for a short time in an electric field. Within a dynamical nonadiabatic evolution method, we simulate the motion of polaron under the influence of the electric field which is present for different periods. We find the lattice oscillation behind the polaron will be localized and separated with the moving polaron once the electric field is turned off. It is shown that the localized lattice oscillation is nothing but a breather, specifically, a moving multibreather excitation. Furthermore, it is the breather which bears the incresed energy due to the electric field acting on the polaron, so that the polaron can move at a constant speed even in the presence of an electric field.