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

Starting from the tight-binding representation of the Hamiltonian of emeral dine salt, which reproduces the electronic structure of the polymer, we inv estigate the nature of its metallic state. We exploit the decimation-renorm alization scheme to work with strictly one-dimensional systems (polymer cha ins and ladder polymers) then, by a proper account of disorder and intercha in effects, we evaluate the transmittivity of the polymer by the T-matrix s cattering approach. Our results support the polaronic model for the metalli c island of emeraldine salt and show that using the same tight-binding para meters, the random dimer model is unable to take the Fermi level of the pol ymer into regions of highly transmitting states. [S0163-1829(99)08947-X].