Effects of distance dependence of exciton hopping on the Davydov soliton

TL;DR

This paper investigates how the distance dependence of exciton hopping affects Davydov solitons in molecular chains, deriving new equations and analyzing their impact on soliton properties and stability.

Contribution

It introduces a modified model with distance-dependent exciton hopping, deriving new equations of motion, and analyzing the resulting effects on soliton characteristics and stability.

Findings

Dilatational soliton amplitude and width decrease with distance dependence.

Localized solutions vanish beyond a critical coupling strength.

Compressional solitons exhibit increased stability.

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 result in the existence of Davydov-like solitons. In the case of a dilatational soliton, the amplitude and width is decreased as a results of the mechanism introduced here and above a critical coupling strength our equations do not allow for localized solutions. For compressional solitons, stability is increased.