Abstract
Results of a priori Hartree–Fock electronic structure calculations on five different polyacetylene models are reported. All significant matrix elements of the one‐ and two‐electron interactions (including the correct and nonlocal exchange) were exactly calculated for a region of ∼120 CH units until every relevant physical property of the polyacetylenes properly converged. The alternating structures are found to be energetically favorable for both the trans‐ and cis‐isomer in this work, the most stable model being the cis‐transoid one. Various one‐ and many‐electron properties as well as the possibilities to obtain reasonably localized Wannier functions for polyacetylenes are discussed.