DISCRETE LATTICE EFFECTS ON BREATHERS IN A SPATIALLY LINEAR POTENTIAL

In the presence of a spatially linear, time dependent potential, we st udy discrete lattice effects on a nonlinear Schrodinger breather in th e form of a composite excitation comprising two soliton components. We obtain an exact breather solution by generalizing the Hirota method t o include the external potential. The solution is a discrete generaliz ation of the two-soliton continuum solution with the initial condition as a superposition of two identical solitons. Unlike the continuum br eather in the presence of a static ramp, the discrete breather will br eak up into two spatially separate, coherent structures undergoing bou nded individual motions. We show that this breakup is a general discre te effect for breathers in an external potential.