Discrete breathers in a model with Morse potentials

Under harmonic approximation, this paper discusses thelinear dispersion relation of the one-dimensional chain. The existenceand evolution of discrete breathers in a general one-dimensionalchain are analysed for two particular examples of soft (Morse) andhard (quartic) on-site potentials. The existence of discretebreathers in one-dimensional and two-dimensional Morse lattices isproved by using rotating wave approximation, local anharmonicapproximation and a numerical method. The localization and amplitudeof discrete breathers in the two-dimensional Morse lattice with on-siteharmonic potentials correlate closely to the Morse parameter a andthe on-site parameter к.