Vibrational activation in associative desorption of hydrogen from Pd(100)

Schröter, L.; Küchenhoff, S.; David, Rudolf; Brenig, Wilhelm; Zacharias, H.

doi:10.1016/0039-6028(92)90236-y

Cited by 35 publications

(27 citation statements)

References 30 publications

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“…The results of these calculations have been compared to a number of independent experiments [16,[39][40][41], and they are at least in semi-quantitative agreement with all of these experiments This shows that ab initio dynamics calculations are indeed capable of adequately describing the hydrogen dissociation on transition metal surfaces.…”

Section: Dissociative Adsorption At a Transition Metal Surfacementioning

confidence: 63%

Hydrogen dissociation on metal surfaces - a model system for reactions on surfaces

Groß¹

1998

Applied Physics A: Materials Science & Processing

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Reactions on surfaces play an important role in many technological applications. Since these processes are often rather complex, one tries to understand single steps of these complicated reactions by investigating simpler system. In particular the hydrogen dissociation on surfaces serves as such a model system. There has been much progress in recent years in the theoretical description of reactions on surfaces by high-dimensional dynamics simulations on potential energy surfaces which are derived from ab initio total energy calculations. In this brief review I will focus on the hydrogen dissociation on the clean and sulfur-covered Pd(100) surface. These calculations established the importance of dynamical concepts like the steering effect. The electronic structure calculations allow furthermore the determination of the factors that determine the reactivity of a particular surface. This will be demonstrated for the poisoning of hydrogen dissociation by sulfur adsorption on the Pd(100) surface. In addition, quantum effects in the dynamics can be assessed by comparing the results of classical with quantum dynamical calculations on the same potential energy surface. 68.35.Ja, 82.20.Kh, 82.65.Pa

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Section: Dissociative Adsorption At a Transition Metal Surfacementioning

confidence: 63%

Hydrogen dissociation on metal surfaces - a model system for reactions on surfaces

Groß¹

1998

Applied Physics A: Materials Science & Processing

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“…In order to explain the vibrational heating, the values for n > 1 in the angular distribution, as well as the increase of the sticking coefficient with the kinetic energy of the H 2 molecules it has been found necessary in dynamic studies on twodimensional model potential-energy surfaces (PES) to assume the presence of a small (about 0.1 eV) barrier in the exit channel, i.e. in the region of the reaction pathway where the H-H bond is already significantly stretched 4,8 . Such an energy barrier, however, yields an additional kinetic energy of thermally desorbing molecules which has not been measured experimentally 4 .…”

Section: Introductionmentioning

confidence: 99%

“…in the region of the reaction pathway where the H-H bond is already significantly stretched 4,8 . Such an energy barrier, however, yields an additional kinetic energy of thermally desorbing molecules which has not been measured experimentally 4 .…”

Section: Introductionmentioning

confidence: 99%

Potential-energy surface forH2dissociation over Pd(100)

1996

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The potential energy surface (PES) of dissociative adsorption of H2 on Pd(100) is investigated using density functional theory and the full-potential linear augmented plane wave (FP-LAPW) method. Several dissociation pathways are identified which have a vanishing energy barrier. A pronounced dependence of the potential energy on "cartwheel" rotations of the molecular axis is found. The calculated PES shows no indication of the presence of a precursor state in front of the surface. Both results indicate that steering effects determine the observed decrease of the sticking coefficient at low energies of the H2 molecules. We show that the topology of the PES is related to the dependence of the covalent H(s)-Pd(d) interactions on the orientation of the H2 molecule.

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“…36͒ on various transition-metal surfaces. In particular, the wellstudied system H 2 /Pd͑100͒, 5,7,25,[37][38][39] which is the subject of our study, belongs to this class. An initially decreasing sticking probability had usually been explained by a precursor mechanism.…”

Section: Introductionmentioning

confidence: 99%

“…40 Still, in lowdimensional dynamical treatments of the H 2 /Pd͑100͒ system no steering effect was observed. [37][38][39] Only very recently it has been shown by high-dimensional quantum-dynamical calculations based on ab initio PES's for the systems H 2 /Pd͑100͒ ͑Refs. 4,8,41͒ and H 2 /W͑100͒ ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

Ab initioquantum and molecular dynamics of the dissociative adsorption of hydrogen on Pd(100)

Groß

Scheffler²

1998

Phys. Rev. B

168

103

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The dissociative adsorption of hydrogen on Pd͑100͒ has been studied by ab initio quantum dynamics and ab initio molecular-dynamics calculations. Treating all hydrogen degrees of freedom as dynamical coordinates implies a high dimensionality and requires statistical averages over thousands of trajectories. An efficient and accurate treatment of such extensive statistics is achieved in a three-step approach: In a first step we evaluate the ab initio potential-energy surface ͑PES͒ for a number of appropriate points in configuration space. Then ͑as step 2͒ we determine an analytical representation that serves as an interpolation between the actually calculated points. In an independent third step dynamical calculations are performed on the analytical representation of the PES. Thus the dissociation dynamics is investigated without any crucial assumption except for the BornOppenheimer approximation which is anyhow employed when density-functional-theory calculations are performed. The ab initio molecular dynamics is compared to detailed quantum-dynamical calculations on exactly the same ab initio PES. The occurence of quantum oscillations in the sticking probability as a function of kinetic energy is addressed. They turn out to be very sensitive to the symmetry of the initial conditions. At low kinetic energies sticking is dominated by the steering effect, which is illustrated using classical trajectories. The steering effect depends on the kinetic energy, but not on the mass of the molecules, as long as no energy transfer to the substrate atoms is considered. The comparison between quantum and classical calculations of the sticking probability shows the importance of zero-point effects in the hydrogen dynamics. The dependence of the sticking probability on the angle of incidence is analyzed; it is found to be in good agreement with experimental data. The results show that the determination of the potential-energy surface combined with high-dimensional dynamical calculations, in which all relevant degrees of freedom are taken into account, leads to a detailed understanding of the dissociation dynamics of hydrogen at a transition metal surface.

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Vibrational activation in associative desorption of hydrogen from Pd(100)

Cited by 35 publications

References 30 publications

Hydrogen dissociation on metal surfaces - a model system for reactions on surfaces

Hydrogen dissociation on metal surfaces - a model system for reactions on surfaces

Potential-energy surface forH2dissociation over Pd(100)

Ab initioquantum and molecular dynamics of the dissociative adsorption of hydrogen on Pd(100)

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