Nonlinear model of intramolecular excitations on a multileg ladder lattice

The exactly integrable model of nonlinear intramolecular excitations on a multileg ladder lattice is proposed. Since it is rather general, the model permits a number of physically interesting ramifications related to the striplike and the bunchlike biological and condensed matter systems as well as to the arrays of linearly and nonlinearly coupled optical fibers. The principal possibility to model an external magnetic field parallel to the ladder legs within the framework of inverse scattering transform is pointed out. The one-soliton solutions of two-leg and three-leg ladder models are found and analyzed. Apart from the spatially constricted translational mode typical to the traditional one-chain soliton, the interchain beating mode as well as the circular traveling modes redistributing the excitations between the chains are revealed in complete accordance with liner limits.