| The arrangement of molecules present an ordered structure in organic molecular crystals,the charge carrier has higher mobility.Therefore,the migration process of organic molecular crystals have attracted widely attention.According to the internal vibration and the intermolecular vibration of the molecule,the phonons can be divided into two types:non-dispersive(Einstein)phonons and dispersive(Debye)phonons.Intramolecular vibration is focused on in Holstein model,i.e.non-dispersive phonons;Intermolecular vibration is focused on in Davydov model,i.e.dispersive phonons.In this paper,the effect of dispersive phonon on the transport properties of organic molecular crystals is investigated based on Holstein model,taking into account the dispersive phonon interaction term.In the process of calculation,the static part are solved by double-conjugate gradient method,and the dynamic part are solved by Rung-Kutta method.The results are as follows:1.The localization and stability of the polaron enhanced by the dispersive electron-phonon(e-ph)coupling?.And the velocity of the polaron decreases under the action of an applied electric field.2.The localization and stability of the polaron are reduced by the dispersive phonon potential?.And the velocity of the polaron increases with an applied electric field.3.The polaron dissociates into a free-like electron under strong electric field,which presents Bloch Oscillation(BO)in a periodic potential field.With the increase of electric field strength,BO is accelerated and the attenuation of BO amplitude becomes faster.Dispersive e-ph coupling makes BO attenuate faster;Dispersive phonon potential makes BO attenuate slower and prolongs its attenuation time.4.An interesting phenomenon is observed in the calculation.When?is greater than0.7,the configuration of the polaron changes and forms a kink polaron.The localization and stability of the kink polaron increase compare to a polaron.So,a higher dissociation electric field is needed for a kink polaron. |
