Electronic structure and optical properties of conducting and semiconducting conjugated oligomers and polymers: An overview of the quantum-mechanical approaches

This contribution aims at providing a broad overview of the quantum-chemistry and density-functional theory techniques that are currently used to describe the electronic structure of conjugated molecules and polymers. Rather than dwelling on detailed mathematical descriptions, we emphasize the limitations and approximations involved in each type of approach and illustrate in which ways different methods are related to one another. A specific example is then discussed in order to illustrate the usefulness of quantum-mechanical calculations in the field of conjugated compounds.