Mode specific electronic friction in dissociative chemisorption on metal surfaces: H2 on Ag(111)

Reinhard J. Maurer, Bin Jiang, Hua Guo, John C. Tully, Phys. Rev. Lett. 118, 256001 (2017)

"Using nonadiabatic ab-initio molecular dynamics, we study how electronic friction affects mode-dependent energy loss and reaction outcomes during dissociative chemisorption of molecular Hydrogen."

Electronic friction and the ensuing nonadiabatic energy loss play an important role in chemical reaction dynamics at metal surfaces. Using molecular dynamics with electronic friction evaluated on-the-fly from Density Functional Theory, we find strong mode dependence and a dominance of nonadiabatic energy loss along the bond stretch coordinate for scattering and dissociative chemisorption of H2 on the Ag(111) surface. Exemplary trajectories with varying initial conditions indicate that this mode-specificity translates into modulated energy loss during a dissociative chemisorption event. Despite minor nonadiabatic energy loss of about 5%, the directionality of friction forces induces dynamical steering that affects individual reaction outcomes, specifically for low-incidence energies and vibrationally excited molecules. Mode-specific friction induces enhanced loss of rovibrational rather than translational energy and will be most visible in its effect on final energy distributions in molecular scattering experiments.

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