Effects of distance dependence of exciton hopping on the Davydov soliton

Abstract The Davydov model of energy transfer in molecular chains is reconsidered assuming the distance dependence of the exciton hopping term. New equations of motion for phonons and excitons are derived within the coherent state approximation. Solving these nonlinear equations results in the existence of Davydov-like solitons. In the case of a dilatational soliton, the amplitude and width is decreased as a result of the mechanism introduced here and above a critical coupling strength our equations do not allow for Davydov-like solutions. For compressional solitons, stability is not affected.