Polyaromatic hydrocarbons with an imperfect aromatic system as catalysts of interstellar H₂formation

Although H2 is the simplest and most abundant molecule in Universe, its formation interstellar medium, especially photodissociation regions far from being fully understood. According to suggestions, of catalysed by polyaromatic hydrocarbons (PAHs) on surface grains. In present study we have investigated catalytic effect small PAHs with an imperfect aromatic system. Quantum chemical computations were performed for H-atom-abstraction H-atom-addition reactions benzene, cyclopentadiene, cycloheptatriene, indene, 1H-phenalene. Heights reaction barriers tunnelling rate constants computed density functional theory using MPWB1K functional. For each molecule, path determined at 50 K ring-polymer instanton theory, temperature dependence was cyclopentadiene cycloheptatriene. The computational results reveal that defects system compared benzene can increase K.