Metal-insulator transition intrans-polyacetylene

Abstract

We have calculated the band structure for a chain of doped trans-polyacetylene using the electronic part of the Su-Schrieffer-Heeger Hamiltonian plus the Coulomb potential arising from ions and charged solitons surrounding the chain. The lattice structure used was that determined by x rays for Na-doped polyacetylene. To agree with a number of experimental observations the donated electrons were taken to be in soliton states at all dopant concentrations. In obtaining the potential of a point charge on a chain in the metallic state, the confinement of the free electrons to a chain was taken into account. Because screening depends on the calculated energy levels, specifically on the density of states at the Fermi energy, η($E_F$), in the metallic state, which, in turn, depend on the potential used to obtain them, self-consistency was required in the calculations.