Nonlinear excitations in pernigraniline, the oxidized form of polyaniline

The electronic structure of fully oxidized polyaniline, pernigraniline, is investigated in the framework of the Su-Schrieffer-Heeger Hamiltonian, making use of an original renormalization technique. Among the family of polyanilines, pernigraniline is the only form to possess a degenerate ground state. It is shown to accomodate elementary excitations of soliton and polaron types having remarkable properties, in some instances markedly different from those predicted for the so-called AB polymer. Nonlinear optical properties of the material are expected to be important.