Full quantum dynamical investigation of the Eley-Rideal reaction forming H2 on a movable graphitic substrate at T =0 K

The dynamics of the Eley-Rideal abstraction reaction of hydrogen atoms on a movable graphitic surface is investigated for the first time in a numerically exact fully quantum setting. A system-bath strategy was applied where the two recombining H atoms and a substrate C atom form a relevant subsystem, while the rest of the lattice takes the form of an independent oscillator bath. High-dimensional wavepacket simulations were performed in the collision energy range 0.2-1.0 eV with the help of the multi-layer multi-configuration time-dependent Hartree method, focusing on the collinear reaction on a zero-temperature surface. Results show that the dynamics is close to a sudden limit in which the reaction is much faster than the substrate motion. Unpuckering of the surface is fast (some tens of fs) but starts only after the formation of H-2 is completed, thereby determining a considerable substrate heating (similar to 0.8 eV per reactive event). Energy partitioning in the product molecule favors translational over vibrational energy, and H-2 molecules are vibrationally hot (similar to 1.5 eV) though to a lesser extent than previously predicted.