The effect of phonon modes on the H2(v, j)/D2(v, j)–Cu(1nn) scattering processes

Sahoo, Tapas; Sardar, Subhankar; Adhikari, Satrajit

doi:10.1039/c0cp00336k

Cited by 18 publications

(37 citation statements)

References 72 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In the ab initio molecular dynamics (AIMD) method the fitting of a high-dimensional PES is avoided, and instead the forces are calculated on the fly. 117,[153][154][155] With this approach there is no correlation between the molecular and lattice motion: at each instance the wave packet describing the molecule only sees an average over the moving surface atoms (i.e., the wave function describing the lattice motion). 141,142 The use of this method to study problems for which surface motion may be relevant has become increasingly popular.…”

Section: D Classical Trajectory Methodsmentioning

confidence: 99%

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

2016

View full text Add to dashboard Cite

We review the state-of-the art in dynamics calculations on the reactive scattering of H2 from metal surfaces, which is an important model system of an elementary reaction that is relevant to heterogeneous catalysis. In many applications, quantum dynamics and classical trajectory calculations are performed within the Born-Oppenheimer static surface model. However, ab initio molecular dynamics (AIMD) is finding increased use in applications aimed at modeling the effect of surface phonons on the dynamics. Molecular dynamics with electronic friction has been used to model the effect of electron-hole pair excitation. Most applications are still based on potential energy surfaces (PESs) or forces computed with density functional theory (DFT), using a density functional within the generalized gradient approximation to the exchange-correlation energy. A new development is the use of a semi-empirical version of DFT (the specific reaction parameter (SRP) approach to DFT). We also discuss the accurate methods that have become available to represent electronic structure data for the molecule-surface interaction in global PESs. It has now become possible to describe highly activated H2 + metal surface reactions with chemical accuracy using the SRP-DFT approach, as has been shown for H2 + Cu(111) and Cu(100). However, chemical accuracy with SRP-DFT has yet to be demonstrated for weakly activated systems like H2 + Ru(0001) and non-activated systems like H2 + Pd(111), for which SRP DFs are not yet available. There is now considerable evidence that electron-hole pair (ehp) excitation does not need to be modeled to achieve the (chemically) accurate calculation of dissociative chemisorption and scattering probabilities. Dynamics calculations show that phonons can be safely neglected in the chemically accurate calculation of sticking probabilities on cold metal surfaces for activated systems, and in the calculation of a number of other observables. However, there is now sufficient evidence to suggest that the decision on whether or not to neglect phonons should be taken with care, with appropriate consideration of the observable to be computed and of the relevant surface temperature. AIMD calculations have provided valuable insights into the mechanisms that are operative in the dissociative adsorption and absorption of hydrogen on/in precovered metal surfaces. Classical and quantum dynamics calculations have shown that the reaction probability of H2 on Pt surfaces consisting of (100) steps and (111) terraces can to a very good approximation be computed as a weighted average of the reactivities on the steps and terraces. Progress obtained with dynamics calculations on the scattering of H2 from alloys and from simple low index metal surfaces is also reported. Insights that may be obtained on the reactivity of a metal surface from the prominent presence of out-of-plane diffraction or, conversely, the complete absence of diffraction, are discussed. A new field has been opened up by experiments on H2 scattering from surfaces at fast graz...

show abstract

Section: D Classical Trajectory Methodsmentioning

confidence: 99%

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

2016

View full text Add to dashboard Cite

show abstract

“…48 Finally, more recently the system has been used to explore the applicability of a mean field quantum dynamics method to investigate the effect of phonons on reactive and non-reactive scattering of H 2 from copper surfaces. 49,50 Here, we present new results of energy resolved rovibrational state selective associative desorption experiments on H 2 desorbing from Cu(100) at a surface temperature (T s ) of 1030 K. An interpretation based on detailed balance allows information to be extracted on the effect of the initial rovibrational state and reagent angular momentum alignment on dissociative chemisorption: Using an improved detection scheme the quadrupole alignment factor A 0 (2) is also obtained as a function of H 2 kinetic energy. These experiments, and the results of the earlier experiments discussed above are compared to results of quantum dynamics calculations using the BOSS model, and employing a PES computed with the SRP functional developed for hydrogen reacting with Cu(111).…”

mentioning

confidence: 99%

Reactive scattering of H2 from Cu(100): Comparison of dynamics calculations based on the specific reaction parameter approach to density functional theory with experiment

Sementa

Wijzenbroek²,

Kolck³

et al. 2013

The Journal of Chemical Physics

201

View full text Add to dashboard Cite

We present new experimental and theoretical results for reactive scattering of dihydrogen from Cu(100). In the new experiments, the associative desorption of H 2 is studied in a velocity resolved and final rovibrational state selected manner, using time-of-flight techniques in combination with resonance-enhanced multi-photon ionization laser detection. Average desorption energies and rotational quadrupole alignment parameters were obtained in this way for a number of (v = 0, 1) rotational states, v being the vibrational quantum number. Results of quantum dynamics calculations based on a potential energy surface computed with a specific reaction parameter (SRP) density functional, which was derived earlier for dihydrogen interacting with Cu (111), are compared with the results of the new experiments and with the results of previous molecular beam experiments on sticking of H 2 and on rovibrationally elastic and inelastic scattering of H 2 and D 2 from Cu(100). The calculations use the Born-Oppenheimer and static surface approximations. With the functional derived semi-empirically for dihydrogen + Cu(111), a chemically accurate description is obtained of the molecular beam experiments on sticking of H 2 on Cu(100), and a highly accurate description is obtained of rovibrationally elastic and inelastic scattering of D 2 from Cu(100) and of the orientational dependence of the reaction of (v = 1, j = 2 − 4) H 2 on Cu(100). This suggests that a SRP density functional derived for H 2 interacting with a specific low index face of a metal will yield accurate results for H 2 reactively scattering from another low index face of the same metal, and that it may also yield accurate results for H 2 interacting with a defected (e.g., stepped) surface of that same metal, in a system of catalytic interest. However, the description that was obtained of the average desorption energies, of rovibrationally elastic and inelastic scattering of H 2 from Cu(100), and of the orientational dependence of reaction of (v = 0, j = 3 − 5, 8) H 2 on Cu(100) compares less well with the available experiments. More research is needed to establish whether more accurate SRP-density functional theory dynamics results can be obtained for these observables if surface atom motion is added to the dynamical model. The experimentally and theoretically found dependence of the rotational quadrupole alignment parameter on the rotational quantum number provides evidence for rotational enhancement of reaction at low translational energies.

show abstract

“…Nonetheless, using the PSA we can still model energy transfer to and from the surface degrees of freedom. A priori, H 2 /Cu seems an ideal system for the PSA, due to the high mass mismatch between the molecule and the substrate atoms and the weak phonon-molecule coupling [56].…”

Section: Quantum Wavepacket Dynamics and Vibrational Sudden Approximamentioning

confidence: 99%

“…Furthermore, Wijzenbroek and Somers pointed out the importance of the temperature of the lattice even at a level at which energy transfer to surface phonons is not allowed, via a simplified molecular dynamics study on the system [62]. Finally, Sahoo et al addressed the problem with an effective hamiltonian derived from a meanfield approximation to the phonon modes and showed the importance of the surface modes directed along the Z-axis [55,56].…”

Section: Introductionmentioning

confidence: 99%

“…The key idea of this approximation, earlier introduced in quantum scattering of H 2 from Pd(100) by Olsen et al [45] and recently applied by Tiwari et al in the case of CH 4 /Ni [60], is to compute the scattering probability as an average of the probabilities computed by fixing the lattice atom in different positions. We prefer this methodology over a mean field approach [55,56] because we can in this way exploit the fact that surface atom motion is slow relative to molecular motion. We will show in the following that our sudden approach is successful and opens the way for the study of higher dimensional dynamical models.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

7D Quantum Dynamics of H₂Scattering from Cu(111): The Accuracy of the Phonon Sudden Approximation

Bonfanti

Somers

Dı́az

et al. 2013

Zeitschrift für Physikalische Chemie

View full text Add to dashboard Cite

The correct prediction of elementary processes occurring when H 2 scatters from a metal surface is one of the main challenges of surface science. In the field, the scattering of H 2 from Cu(111) has been considered a prototype system for activated dissociative chemisorption. Experimental and theoretical work suggested that a proper description of some scattering experiments on this system might require going beyond the static surface approximation, to consider how the motion of the Cu atoms affects the scattering event. Previous work suggested that important effects of phonons on the dynamics can be incorporated in the Potential Energy Surface (PES) by including four degrees of freedom, that have approximately additive couplings with the hydrogen molecule: the 3 dimensional motion of the nearest 1 st layer copper atom and the displacement of the nearest 2 nd layer copper atom along the direction perpendicular to the surface [3]. In the present work, we extend the 6D dynamical model by including the perpendicular motion of the 2 nd layer surface atom and we study this novel dynamical model with two techniques: an approximate method based on the Phonon Sudden Approximation (PSA) and an exact description using 7D wavepacket quantum dynamics. We consider how the inclusion and the excitation of the lattice degree of freedom affect some relevant processes: dissociative chemisorption, vibrational excitation of H 2 and state-to-state scattering probabilities fully resolved with respect to the vibrational states of the surface. We show that the PSA works in an excellent way for the system, thereby suggesting that this might be a viable way to study higher dimensional quantum models, incorporating four surface degrees of freedom that appear to be most relevant for H 2 scattering.

show abstract

The effect of phonon modes on the H2(v, j)/D2(v, j)–Cu(1nn) scattering processes

Cited by 18 publications

References 72 publications

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

Reactive scattering of H2 from Cu(100): Comparison of dynamics calculations based on the specific reaction parameter approach to density functional theory with experiment

7D Quantum Dynamics of H₂Scattering from Cu(111): The Accuracy of the Phonon Sudden Approximation

Contact Info

Product

Resources

About

The effect of phonon modes on the H2(v, j)/D2(v, j)–Cu(1nn) scattering processes

Cited by 18 publications

References 72 publications

Quantum and classical dynamics of reactive scattering of H2 from metal surfaces

Quantum and classical dynamics of reactive scattering of H2 from metal surfaces

Reactive scattering of H2 from Cu(100): Comparison of dynamics calculations based on the specific reaction parameter approach to density functional theory with experiment

7D Quantum Dynamics of H2Scattering from Cu(111): The Accuracy of the Phonon Sudden Approximation

Contact Info

Product

Resources

About

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

7D Quantum Dynamics of H₂Scattering from Cu(111): The Accuracy of the Phonon Sudden Approximation