Time-Dependent Quantum Mechanical Calculations on the Formation of Molecular Hydrogen on a Graphite Surface via an Eley−Rideal Mechanism

The associative desorption of H 2 (ν, j ) on a graphite(0001) surface via an Eley−Rideal mechanism has been studied theoretically. In our calculations we used a time-dependent wave packet method treating three degrees of freedom quantum mechanically. A newly developed potential energy surface based on plane-wave density functional calculations was employed. In our 3D calculations we find less vibrational excitation for the product H 2 molecules than in calculations that used only two degrees of freedom. However, the product H 2 molecules are formed rotationally excited. This could have important implications for the chemistry of H 2 in the interstellar medium and the interpretation of astronomical data.