Theoretical investigation of neutral and charged defects in the pernigraniline base form of polyaniline

Summary form only given. The pernigraniline base form of polyaniline is nowadays extensively investigated in order to determine the nature of the charge-storage species in this degenerate ground-state material. In this contribution, we present the results of Austin Model 1 (AM1) and Valence Effective Hamiltonian (VEH) quantum-chemical calculations on pernigraniline oligomers; our aim is to describe theoretically the geometric and electronic structure of the charged defects (positively and negatively charged polarons and solitons) which can appear upon p- and n-doping. We also focus on the description of the neutral solitons which have been recently observed in photoinduced absorption measurements. All our results are compared to experimental data, with the goal of understanding the influence of structural parameters, in particular bond lengths and torsion angles, on the electronic characteristics of pernigraniline. We also try and provide a better understanding of the origin of the large defect masses observed in this polymer.