Kinks and polarons in polyacetylene

Various defect states in a finite trans‐polyacetylene chain are studied by a geometry optimization method with a tight‐binding Hamiltonian of Longuet‐Higgins and Salem. It is shown that the defect obtained forms a φ‐four kink or two combined kinks such as a polaron, being independent of chain size whenever the chains are longer than the defect width. The defect formation energy is local in the vicinity of the defect. The creation energies of the kink and polaron at rest have been determined by means of extrapolation to infinite chain size. The results obtained are in good agreement with those estimated from the analytical solutions in the continuum models.