<i>A</i> <i>b</i> <i>i</i> <i>n</i> <i>i</i> <i>t</i> <i>i</i> <i>o</i> calculations of correlation effects in <i>t</i> <i>r</i> <i>a</i> <i>n</i> <i>s</i>-polyacetylene

Abstract

The fundamental band gap and the exciton binding energies of t-PA have been evaluated with the aid of ab initio Hartree–Fock plus Mo/ller–Plesset perturbation theoretical calculations. The irreducible self-energy part has been expanded up to third order and the irreducible vertex part has been expanded up to second order. The results support one of several controversial assignments of the ∼2 eV peak in the experimental absorption spectrum of trans-polyacetylene, namely that to interband transitions.