DISCRETE NONLINEAR EXCITATIONS ON AN INHOMOGENEOUS LATTICE IN A SPATIALLY LINEAR POTENTIAL

Discrete nonlinear excitations on an inhomogeneous lattice in a spatia lly linear potential are investigated. Discrete breathers possessing m ultiple frequencies are always spatially localized and oscillatory in lime, with oscillatory frequencies depending on an external potential. A number of phenomena associated with the translational symmetry of t he system is addressed. The spatially localized, time periodic and qua si-periodic nonlinear coherent excitations comprising multiple-soliton components are presented with exact results for the corresponding ene rgy, momentum and norm. The mean width of a pulse as a measure of loca lization is also studied.