Importance of chain-chain interactions on the band gap of trans-polyacetylene as predicted by second-order perturbation theory

The Laplace-transformed second-order MØller-Plesset perturbation theory was used for periodic systems in its atomic orbital basis formulation for investigating the geometric structure and band gap of interacting polyacetylene chains. The equilibrium interchain distance and setting angle, along with binding energy between trans-polyacetylene chains were estimated from the first principles. The dependence of the correlation corrected quasiparticle band gap on the interchain and intrachain geometric parameters was also studied. The results show that the gap of the compound structures is reduced with respect to the single chain polymer.