Electron interaction in conducting polymers and its effect on dimerization

Abstract

There appears a sharp dispute recently, one side affirms that the electron interaction suppresses the dimerization of the conducting polymers, but the other side insists the opposite opinion that the electron interaction enhances the dimerization. In order to settle this dispute, it is crucial to reexamine the description of the electron-electron interaction. Since the bandwidth of the conducting polymers is larger than the electron interaction, the electron interaction should be described by the full Coulomb interaction with certain screening rather than the Hubbard model. Based on the full interaction, we obtain the dependences of the dimerization on the interaction strength U 0 and the screening factor β of the electron interaction. Our results clarify the above dispute in this way: There exists a critical length Δ C for the interaction range Δ = a β (a is the lattice constant), Δ> Δ C, the dlmerlzation Is enhanced by the electron interaction. Δ< Δ C, the dimerization will be reduced by the electron interaction. The critical length Δ C is of the order of the lattice constant. When the bandwidth increases, Δ C will become longer.