Reactive and nonreactive scattering of N2 from Ru(0001): A six-dimensional adiabatic study

Abstract

). Reactive and nonreactive scattering of N-2 from Ru(0001): A six-dimensional adiabatic study. Journal of Chemical Physics, 125(11), 114706. DOI: 10.1063/1.2229197 Reactive and nonreactive scattering of N 2 from Ru"0001…: A six-dimensional adiabatic study We have studied the dissociative chemisorption and scattering of N 2 on and from Ru͑0001͒, using a six-dimensional quasiclassical trajectory method. The potential energy surface, which depends on all the molecular degrees of freedom, has been built applying a modified Shepard interpolation method to a data set of results from density functional theory, employing the RPBE generalized gradient approximation. The frozen surface and Born-Oppenheimer ͓Ann. Phys. ͑Leipzig͒ 84, 457 ͑1927͔͒ approximations were used, neglecting phonons and electron-hole pair excitations. Dissociative chemisorption probabilities are found to be very small even for translational energies much higher than the minimum reaction barrier, in good agreement with experiment. A comparison to previous low dimensional calculations shows the importance of taking into account the multidimensional effects of N 2 rotation and translation parallel to the surface.

A note on the vibrational efficacy in molecule-surface reactions

“…[29] With this as a basis the experimental data could still be consistent with a vibrational efficacy less than or equal to one. [29] However, theoretical results for N 2 dissociation on Ru(0001) indicates that the asymptotic reactivity is about the same for the different molecular vibrational states, [30] The goal of our present contribution is to show that there is actually nothing surprising about finding Θ vib (R) > 1. We will do this by providing rather straightforward considerations along the lines already suggested by Smith and coworkers, [24] leading to the conclusion that the vibrational efficacy is not limited either from below or above.…”

“…The cutoff energy for the plane wave basis was set to 350 eV and to sample the Brillouin zone 18 Chadi-Cohen [39] kpoints were used. Extensive testing of all computational parameters at a number of selected configurations shows that the molecule-surface interaction energies are converged within 0.1 eV [30,31], a typical error bar for these type of DFT calculations. [40][41][42] B. Quasi-classical dynamics Classical dynamics is a very powerful tool for the kind of study we have carried out here.…”

“…30 and 31, these theoretical results reproduce the surprisingly low dissociation probabilities [27,[50][51][52] found in the experiments. The results can be understood based on the very special characteristics of the N 2 /Ru(0001) PES: [28,30,31,51] The minimum barrier is very high, around 2.3 eV, and the PES displays high anisotropy and corrugation, i.e., small changes in the orientation and/or the position of the molecule gives rise to large changes in the potential energy (see Fig. 3 in Ref.…”

“…Detailed accounts of our six-dimensional (6D) PES for N 2 /Ru(0001) has been published elsewhere, [30,31] thus only a brief summary of the main characteristics is provided here.…”

Vibrational deexcitation and rotational excitation of H2 and D2 scattered from Cu(111): Adiabatic versus non-adiabatic dynamics

“…[16][17][18][19][20][21][22][23][24] In some cases, non-adiabatic dynamics based on low-dimensional calculations has resulted in overestimation of the effects associated with e-h pair excitations. For example, for N 2 /Ru(0001) it was claimed, 16 based on low-dimensional non-adiabatic calculations, that the huge discrepancy between low-dimensional adiabatic calculations and experiment was mostly due to e-h pair excitations, whereas a subsequent adiabatic high-dimensional dynamics study 25,26 showed that most of the discrepancy vanishes when the six degrees of freedom of the molecule are taken into account in the dynamics. Six-dimensional (6D) adiabatic calculations have also been able to reproduce, for instance, experimental measurements of reactive and non-reactive scattering of H 2 from Pt(111) (Ref.…”