Convergence In Self-Consistent Study Of Polaron Formation In Conjugated Polymers

Conjugated Polymer as a new functional materials, with both the electronic properties of metals and semiconductors, but also has the easy processing of organic plastic, the mechanical characteristics of flexibility and become a research hotspot in recent decades.Different from traditional inorganic materials, organic conjugated polymers with strong electron-lattice interaction, electron doping or excitation will lead to lattice distortion. Therefore, the doped polymer carrier is no longer the electrons or holes, but the soliton, polaron, bipolaron and other electron-lattice coupling state.Currently, a large number of synthetic polymer as the same as cis-polyacetylene, the ground state is non-degenerate state, which resulted in the most basic carrier of these substances is the polaron, rather than solitons. So the research on the polaron has more general meaning.A self-consistent method was used to simulate polaron formation process in one dimensional (1D) conjugated polymer chains. The relation between the initial lattice configuration and the convergence of the numerical iteration method was studied. It is found that if the initial 1D crystal lattice has a regularly zigzagged change in bond length, the convergence precision is much greater for a closed chain than for an open chain. This indicates that the longer the organic chain the slower the convergence process. For a closed chain, the convergence of the self-consistent iteration to form a polaron is favored by reducing the symmetry of the lattice system. In the presence of impurity, we found the astringency of the iteration has close relation with the doping site. As the doping occurs around the center, the iteration is monotonically convergent. However as doping occurs at other positions, the iteration process has a peak, which postpones the iteration process. Our results show that carrier formation in 1D organic molecular chain has close relation with the initial lattice configuration as well as with the environment around the chain, which actually suggests that in more complicated organic materials, there exists new type of compound carriers.