Formation of H2 on polycyclic aromatic hydrocarbons under conditions of the ISM: an ab initio molecular dynamics study

Abstract Understanding how the H2 molecule is formed under chemical conditions of interstellar media (ISM) critical to whole chemistry it. Formation in ISM requires a third body acting as reservoir energy. Polycyclic aromatic hydrocarbons (PAHs) are excellent candidates play that role. In this work we simulated collisions hydrogen atoms with coronene form via Eley-Rideal mechanism. To do so, used Born-Oppenheimer (ab initio) Molecular Dynamics simulations. Our results show adsorption H and subsequent release readily happen on for kinetic energy large 1 eV. Special attention paid dissipation partition released reactions. The capacity dissipate collision reaction energies depends varies site. Inner sites easier faster than edge sites, thus evidencing an interplay between potential surface around center its ability cool projectile. As recombination formation H2, it observed $\sim 15~{{\ \rm per\ cent}}$ dissipated by vibrational remaining carried H2. molecules desorb from excited state (υ ≥ 3), amount translational (≥ 0.4 eV) small activation rotational degree freedom.