Dresden 2006 – scientific programme

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DY: Dynamik und Statistische Physik

DY 46: Poster

DY 46.126: Poster

Thursday, March 30, 2006, 16:00–18:00, P1

Internal dynamics and complex motion of nonlinear excitations in a highly dispersive near-discrete medium — •Oksana Charkina and Mikhail Bogdan — B.Verkin Institute for Low Temperature Physics and Engineering of NAS of Ukraine, 47 Lenin Ave., Kharkov 61103, Ukraine

The strong spatial dispersion in crystals can change drastically dynamic properties of nonlinear excitations. A typical example of the excitations in an imperfect lattice is a dislocation, which can be considered as a soliton (kink) of the Frenkel-Kontorova model. In the system with the strong dispersion solitons exhibit a complex intrinsic structure with internal degrees of freedom. To succeed in analytical description of the novel effect a fourth-order spatio-temporal derivative is added to the usual sine-Gordon equation. This approach allows us to find exactly a total spectrum of linear excitations of the kink. It consists of a discrete set of frequencies of internal modes and a single band spectrum of continuum waves. It is shown analytically and numerically that a translational motion of a single soliton in the dispersive system is accompanied by exciting its internal dynamics and creation of the breather state, and by generation of the radiation. It is demonstrated that a fast motion of two identical solitons leads to a formation of the bound soliton complex, which is stable and can move radiationlessly in the highly dispersive sine-Gordon system.