Mechanisms for the growth of polycyclic aromatic hydrocarbon (PAH) cations

The barriers and heats of reaction for the conversion of benzene cation to naphthalene cation by acetylene additions using the B3LYP/6-31G* approach are reported. The barrierless path we previously reported, using the B3LYP/4-31G approach, is shown to be incorrect. New paths for the ring formation are shown to have low barriers.