Dynamics of H2 dissociation on the close-packed (111) surface of the noblest metal: H2 + Au(111)

Abstract

We have performed calculations on the dissociative chemisorption of H on un-reconstructed and reconstructed Au(111) with density functional theory, and dynamics calculations on this process on un-reconstructed Au(111). Due to a very late barrier for dissociation, H + Au(111) is a candidate H-metal system for which the dissociative chemisorption could be considerably affected by the energy transfer to electron-hole pairs. Minimum barrier geometries and potential energy surfaces were computed for six density functionals. The functionals tested yield minimum barrier heights in the range of 1.15-1.6 eV, and barriers that are even later than found for the similar H + Cu(111) system. The potential energy surfaces have been used in quasi-classical trajectory calculations of the initial (v,J) state resolved reaction probability for several vibrational states v and rotational states J of H and D. Our calculations may serve as predictions for state-resolved associative desorption experiments, from which initial state-resolved dissociative chemisorption probabilities can be extracted by invoking detailed balance. The vibrational efficacy η reported for D dissociating on un-reconstructed Au(111) (about 0.9) is similar to that found in earlier quantum dynamics calculations on H + Ag(111), but larger than found for D + Cu(111). With the two functionals tested most extensively, the reactivity of H and D exhibits an almost monotonic increase with increasing rotational quantum number J. Test calculations suggest that, for chemical accuracy (1 kcal/mol), the herringbone reconstruction of Au(111) should be modeled.

Mode Specific Electronic Friction in Dissociative Chemisorption on Metal Surfaces: H2 on Ag(111)

“…We select H 2 on Ag(111) as a prototypical example of DC, because EHPs are believed reaction coordinate to play a larger role on coinage metal surfaces, where the dissociation barrier lies closer to the surface. [13,30] Indeed, we find electronic friction to act dominantly along the intramolecular stretch motion as the molecule dissociates. As a consequence, electronic friction induces modulated energy loss during scattering events.…”

Test of the Transferability of the Specific Reaction Parameter Functional for H2 + Cu(111) to D2 + Ag(111)

“…The DFT procedure and the way the data are interpolated are almost entirely the same as those used before for H 2 + Au(111). 13 Here, we describe only the most important aspects and provide a few details on which the present procedure differs from that used earlier.…”

“…The low starting value of r was needed because high initial vibrational states were involved in the Boltzmann sampling of the molecular beam simulations. We extended the H–H distance to a lower bound than that used for H 2 + Au(111) 13 to guarantee the accurate calculation of higher vibrationally excited states (see below). In all other aspects, the procedure followed to produce the DFT data on grids of points and to interpolate the points with the CRP is entirely analogous to that used earlier for H 2 + Au(111).…”

“… 12 A previous study using the SRP48 functional computed initial-state selected reaction probabilities for H 2 + Au(111) using quasi-classical dynamics. 13 Subsequent associative desorption experiments measured initial-state selected reaction probabilities that were shifted to substantially lower translational energies. 14 These results suggest that the SRP48 functional is not transferable from H 2 + Cu(111) to H 2 + Au(111).…”

Nuclear quantum effects on adsorption of H2 and isotopologues on metal ions

“…As another example, Jordan and co-workers [7,8,9] demonstrate that classical simulations of H 2 interacting with Li-doped benzene yields more favorable H 2 binding and an incorrect temperature dependence of thermochemical properties compared to the quantum simulations. NQE also play a role in dissociation of H 2 on Au(111) surface [10].…”