Polarons general discussion

The new states can either be interpreted in the band picture as polarons and/or bipolarons which occur due to electron-phonon coupling after ionization (see below) (electron-electron interaction is neglected) or as the new HOMO and LUMO states in charged particles if localized molecular orbitals are assumed (electron-electron correlation is taken into account, electron-phonon coupling neglected). Both models will be discussed in parallel in the following subsections. However, in general discussions the band stmeture terms will be used as they are more common in literature. 

The concept of the polaronic metal has been applied to polyaniline as well, and may be a more general feature of the metallic state in conducting polymers. In the context of the discussions presented in Section I through Section IV, the polaronic metal is indeed a "metal" and the analysis given is appropriate. In particular, the importance of the selforganization of the doped polymer (to avoid counter-ion scattering) and the need to avoid localization etc. are of clear importance. 

ABSTRACT. The general concepts of quasi-one-dimensional conducting polymers are introduced including the role of band theory, electron-phonon interactions, the Peierls ground state, and commensurability. The dominant defect states present upon doping, solitons, polarons and bipolarons, are discussed. Application of these concepts to polyaniline is made with emphasis on the mechanism for the insulator-to-metal transition. 

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