Soliton dynamics of an extended ϕ4model with dissipation and an external field

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Abstract
The authors present an analytical and numerical study of the dynamics of the nonlinear excitations in an extended phi 4 nonlinear chain with a constant external field including nonlinear inter-particle coupling along the chain. In the absence of damping the kink is accelerated but its velocity is limited by the emission of sound waves, due to narrowing of the kink. The stability of envelope solitons in the presence of the external field and as a function of the potential parameters is examined. With dissipation the kinks move uniformly with a field-dependent velocity except at high fields. For a dimerised interaction between nearest neighbours they obtain small-amplitude 'optical kinks' whose dynamics are studied. Finally, the results are generalised for a diatomic chain and possible extensions and applications for hydrogen-bonded chains are discussed.