Theoretical investigation of thiophene oligomers: A spin-coupled study

The electronic structure of thiophene oligomers is analyzed within the framework of spin-coupled theory. The pi valence electrons are correlated for either one or two central thiophene rings embedded in oligomers ranging up to six units. The localized nature of the spin-coupled orbitals, together with a proper account of the embedding, makes it possible to obtain a set of orbitals which can be transferred from smaller oligomers to larger ones. In this way, we obtain orbitals that may be considered a good approximation to those of the polymer.