Tight-binding effective Hamiltonians for the electronic states of polyaniline chains

By means of strictly one-dimensional effective Hamiltonians, in the tight-binding scheme, we obtain band structures and densities of states of the main forms of polyanilines, which compare favourably with existing theoretical and experimental studies. We first consider the band structures of the three polymeric base forms: leucoemeraldine, emeraldine and pernigraniline; then we study the pernigraniline salt and the emeraldine salt in the polaronic and bipolaronic configurations. The 1D π-electron effective Hamiltonians are obtained exploiting a modified version of the recursion method and successively the application of the renormalization method. The procedure here outlined can be adopted for any polymeric chain; it is so flexible to embody known relevant structural and optical properties of the polymer, moreover it provides a useful tool for successive iterative calculations in the study of the electronic transport properties of the polymer also in the presence of disorder.