Abstract
Electron-correlation effects in the photoelectron spectrum of polyacetylene are analyzed. Hole mixing and breakdown of the one-particle picture are obtained and interpreted by means of ab initio Green’s-function calculations based on canonical crystal orbitals. The results represent explicit theoretical evidence that electron correlation effects are essential for an understanding of the photoelectron spectrum of polyacetylene at binding energies larger than 17 eV with respect to the Fermi level.