Ground-state potential energy curves of phenylenevinylene oligomers Original Research Article

In this paper we calculate the energies of the different configurations of a poly(p-phenylene vinylene) trimer (OPV3) using ab inito Hartree–Fock (HF) methods. In order to determine sufficiently the energy configurations of the trimer, we used two dihedral angles, θ and φ, as variables of the potential energy surface, as opposed to a single dihedral angle as commonly found in the literature. We also determine the effects of the number of monomer units to the rotational barrier. We show that stilbene is not long enough to fully account for conjugation effects in the rotation of a phenyl ring within a polymer. In addition to this, we also show that computationally intensive calculations of oligomers longer than trimers are unnecessary in determining the energetics of a segment in a PPV chain.