抄録
We present a theory for the metallic phase of heavily doped polyacetylene. The Hartree-Fock (HF) ground state in this system is a charged soliton (S±) lattice that has a nearly periodic long range order in the charge density as well as the one in lattice distortion. We take account of electronic correlation effects by considering superpolarons (SP’s) as local fluctuations in the electronic order parameter (OP). They are electrons and holes injected into a S± lattice that make no lattice distortions but are selftrapped and make local defects in the electronic OP. They make intrachain quantum translation and interchain hopping through dopants. The formation energy of a SP pair is reduced by these quantum motions and become negative in a high doping regime. Therefore, the ground state in this regime is a S± lattice with spontaneously produced SP’s. The SP’s may be regarded as Fermion quasi-particles. Since they partially occupy the translational bands of SP’s, metallic properties appear in this phase.
