Effect of nonlinearity on the dynamics of a particle in dc field-induced systems

TL;DR

This paper investigates how nonlinearity influences the dynamics and localization of a particle in a nonlinear chain under a dc field, revealing different regimes and a self-trapping transition.

Contribution

It provides a numerical analysis of nonlinear effects on particle dynamics in dc field systems, identifying regimes where nonlinearity reduces or enhances localization.

Findings

Nonlinearity causes different dynamical regimes depending on its strength.

A critical nonlinear strength induces a self-trapping transition.

Beyond the transition, nonlinearity enhances localization.

Abstract

Dynamics of a particle in a perfect chain with one nonlinear impurity and in a perfect nonlinear chain under the action of dc field is studied numerically. The nonlinearity appears due to the coupling of the electronic motion to optical oscillators which are treated in adiabatic approximation. We study for both the low and high values of field strength. Three different range of nonlinearity is obtained where the dynamics is different. In low and intermediate range of nonlinearity, it reduces the localization. In fact in the intermediate range subdiffusive behavior in the perfect nonlinear chain is obtained for a long time. In all the cases a critical value of nonlinear strength exists where self-trapping transition takes place. This critical value depends on the system and the field strength. Beyond the self-trapping transition nonlinearity enhances the localization.