Spectral Analysis of Polaron Dynamics in Conjugated Polymers

Abstract

To understand the dynamic properties of polaron in conjugated polymers, we have investigated various spectra of electric current density, charge density, and lattice vibrations of acoustic and optic modes based on the Su–Schrieffer–Heeger model, by using nonadiabatic molecular dynamics and power-spectrum density methods. A series of characteristic peaks have been identified. In the spectrum of current density, besides the fact that the amplitude of the zero-frequency peak corresponds to the average velocity of the polaron as expected, it is also found that the fundamental frequency is proportional to the polaron velocity. Furthermore, in the case of low electric field strength, the spectra of charge density and acoustic and optic modes present a similar structure as that of the current density, which implies the charge is coupled with both acoustic and optic modes, and the polaron moves at a slightly lower velocity than the speed of the phonon. However, when the electric field increases beyond a critical ...