The one‐dimensional intersoliton electron tunneling conduction model in doped polyacetylene, which is a semiconductor‐metal transition mechanism, is proposed. With this model, the observed two transition concentrations (y = 0.001 and y = 0.05) can be estimated correctly. In the lightly doped regime (y < 0.001), the three‐dimensional intersoliton electron hopping conduction is dominant. At the intermediate concentration regime (0.001 < y < 0.05), the electrons (or holes dopending on the dopants) can tunnel through the pinned solitons within a single chain. These tunneling charge carriers contribute to the high conductivity. But these tunneling charge carriers can give no Pauli susceptibility since they are not band‐type carriers. Instead, they are transient carriers tunneling between the two soliton sites. Finally, in the high concentration regime (y > 0.05), the pinned soliton wave function can overlap each other forming a soliton liquid. In this stage, the bond alternation of the trans‐polyacetylene chain vanishes being equivalent to the uniform bond length chain. Therefore, the metallic conductivity and finite Pauli susceptibility are expected consistent with the observed experimental results. However, since this metallic state is formed by the soliton liquid it is not a single particle like metal. The internal vibrational modes and other signals characteristic to the soliton can persist in the metallic polyacetylene. Copyright © 1990 Hüthig & Wepf Verlag
