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

By means of strictly one-dimensional effective Hamiltonians, in the tight-b inding scheme, we obtain band structures and densities of states of the mai n forms of polyanilines, which compare favourably with existing theoretical and experimental studies. We first consider the band structures of the thr ee polymeric base forms: leucoemeraldine, emeraldine and pernigraniline; th en we study the pernigraniline salt and the emeraldine salt in the polaroni c and bipolaronic configurations. The 1D pi -electron effective Hamiltonian s are obtained exploiting a modified version of the recursion method and su ccessively the application of the renormalization method. The procedure her e outlined can be adopted for any polymeric chain; it is so flexible to emb ody known relevant structural and optical properties of the polymer, moreov er it provides a useful tool for successive iterative calculations in the s tudy of the electronic transport properties of the polymer also in the pres ence of disorder.