Transport properties of emeraldine salts: The nature of the metallic state

Starting from the tight-binding representation of the Hamiltonian of emeraldine salt, which reproduces the electronic structure of the polymer, we investigate the nature of its metallic state. We exploit the decimation- renormalization scheme to work with strictly one-dimensional systems (polymer chains and ladder polymers) then, by a proper account of disorder and interchain effects, we evaluate the transmittivity of the polymer by the T-matrix scattering approach. Our results support the polaronic model for the metallic island of emeraldine salt and show that using the same tight-binding parameters, the random dimer model is unable to take the Fermi level of the polymer into regions of highly transmitting states.