Theoretical study of torsion and its effect on the structural and electronic properties of cyano-substituted poly(p-phenylene vinylene) and its derivatives

We report the results of a theoretical study on torsion and its effect on the structural and electronic properties of cyano-substituted poly(p-phenylene vinylene) and its dimethoxy and dimethyl ring-substituted derivatives. Geometries, inter-ring torsion potentials, and potentials associated with torsion of the ring substituents are calculated using the semiempirical quantum-chemical Austin model 1 method. The evolution of the bandgap, ionization potential, and electron affinity is evaluated using the pseudopotential valence effective Hamiltonian method.