Density-functional theory study of electronic and structural properties of doped polypyrroles

Electronic and structural properties of polypyrroles oxidized by different concentrations of chlorine atoms or molecules are studied with the use of a density functional method implemented with plane waves and pseudo-potentials for the core electrons. The calculated properties are compared with those obtained for the neutral system that are in good agreement with the available experimental data. The role of the counterion in the oxidation process is studied extensively and shown to be crucial for the localization of charge and structural defects.