Effects Of Dephasing On The Dynamics Of Polaron

Organic molecular crystals exhibit high carrier mobility due to their high orderliness.This characteristic makes the transport properties of polaron in organic crystals attract widespread attention.According to whether the phase of the electronic wave function changes,the carrier transport in the organic molecular crystal can be divided into two types:coherent transport and incoherent transport.The type in which the electronic phase remains unchanged belongs to the coherent transport,and the phase change belongs to the non-coherent transport.Based on the Holstein model of organic molecular crystals,the effect of decoherence effect on the dynamics of polarons was studied using non-adiabatic molecular dynamics methods.In a certain decoherence time,the decoherence effect is achieved by introducing a random phase factor in the electronic wave function.The effects of the decoherence factor on the stability of the polaron without external field,the influence of the decoherence factor on the polaron dynamics under the weak electric field and the influence of the strong electric field on the Bloch oscillation behavior were studied.In addition,the effects of decoherence on the dynamics of polarons under different electro-acoustic coupling strengths k,adiabatic factors?,and the strength of applied electric field₀F are discussed.The specific findings are as follows:1.When no electric field is applied,the decoherence causes the polarization center position to shift,weakening the local degree,and deteriorating the stability.The shorter the decoherence time,the larger the phase fluctuation,the weaker the localization of the polaron,and the poorer the stability.2.Under the weak electric field,the system forms localized polarons and moves under the action of an electric field to form a current.The decoherence effect makes the stable current formed by the system significantly oscillate,and the stable current value increases slightly with the decrease of the decoherence time and the increase of the phase fluctuation amplitude.In addition,the effects of system decoherence factors on the polaron dynamics under different electro-acoustic coupling strengths and adiabatic factors were studied.As the electro-acoustic coupling strength increases,the oscillation amplitude of the stable current3.part increases,the more obvious the oscillation,the more unstable the current,the more obvious the decoherence effect.When the adiabatic factor is small,the oscillation of the stable current is more frequent,the larger the oscillation amplitude,and the more unstable the current,so the effect of the decoherence is more obvious when the adiabatic factor is small.4.Under the externally-enhanced electric field,the polaron formed by the system dissociates and exhibits Bloch oscillation behavior under the strong field.Because the decoherence factor destroys the phase information of the system,the amplitude of the Bloch oscillation of the current decays.In addition,the influence of system decoherence factors on Bloch oscillation under different electro-acoustic coupling strengths and adiabatic factors was also studied.The Bloch oscillation amplitude of the current density increases with the electro-acoustic coupling.The attenuation amplitude increases with and without the decoherence factor.As the adiabatic factor increases,the amplitude of the Bloch oscillation of the current density decays more significantly.