Soliton radiation and role of the energy dissipation in soliton dynamics in an oscillating magnetic field

Abstract: Dynamics of the Davydov's soliton in an external oscillating in time magnetic field is studied analytically. It is shown that in a field perpendicular to the molecular chain axis, soliton wavefunction is a product of the electron plane wave in the plane perpendicular to the molecular chain, and longitudinal component of the wavefunction which satisfies the modified nonlinear Schroedinger equation with an extra term determined by the field. It is shown that soliton width and amplitude are constant, while its velocity and phase are oscillating functions of time with the frequency of the main harmonic equal to the magnetic field frequency. It is shown that soliton dynamics has two different regimes at low and high frequencies of the magnetic field as comparing with the characteristic soliton frequency. Due to time-depending velocity and nonzero acceleration, soliton radiates linear waves in both directions from its center of mass. In the presence of energy dissipation, soliton velocity is bound from above due to the balance of the energy gain from the magnetic field, and its loss because of the dissipation and radiation of linear sound waves. This balance occurs at the resonant frequency of the magnetic field. It is concluded that such significant impact of time-depending magnetic field on charge transport, provided by solitons, can affect functioning of the devices based on low-dimensional moolecular systems. These results suggest the physical mechanism of therapeutic effects of oscillating magnetic fields.