The quantum dynamics of H2 on Cu(111) at a surface temperature of 925 K: Comparing state-of-the-art theory to state-of-the-art experiments

Abstract

We present results on our recently expanded static corrugation model (SCM) approach to including the relevant surface temperature effects, applied to the dissociative chemisorption reaction of H2 on a Cu(111). The reaction and rovibrationally elastic scattering probabilities we obtain at a quantum dynamical (QD) level, as an average of many statically distorted surface configurations, show great agreement with those of a dynamic surface model, which reinforces the validity of the sudden approximation inherent to the SCM. We further investigate several simple methods of binning the final rovibrational state of quasi-classical dynamics simulations, to find those best suited to reproduce QD results for our system. Finally, we show that the SCM obtained results reproduce experimental dissociation curves very well, when the uncertainty in experimental saturation values are taken into account. Some indication of a slow channel, so far only observed in experiment, can also be found at low incidence energies, although more rigorous QD simulations are required to reduce the noise inherent to our propagation methods.

Machine Learning Interatomic Potentials for Reactive Hydrogen Dynamics at Metal Surfaces Based on Iterative Refinement of Reaction Probabilities

“…Sticking probabilities of H 2 on Cu(111) have also been measured by Kaufmann et al at 923 ± 3 K. Within theoretical studies, the majority of references are based on the BOSS approximation and effective phonon corrections, which become increasingly inaccurate at elevated surface temperatures . However, a recent QCD-EAM-DCM reported by Smits and Somers . accounted for surface degrees of freedom.…”

“…Additionally, CRP models have reduced dimensionality, typically including only the molecular degrees of freedom while keeping the surface frozen. While approximate approaches to include phonon and temperature effects have been proposed, ,− ,, the accuracy and efficiency of these approximations have to be verified for each system. The modified Shepard interpolation method was found to have symmetry-related issues, which have been addressed in a H 2 /Pd­(111) study .…”

“…Initially, the works that investigated hydrogen dynamics at Cu surfaces employed generalized gradient approximation functionals such as PW91 or RPBE. ,, However, it was observed that RPBE underestimates and PW91 overestimates reaction probabilities for H 2 dissociation at Cu(111) surfaces . In order to address this issue for hydrogen surface chemistry, the specific reaction parameter (SRP) functional was developed and applied in many studies of dissociation at the Cu(111) surface. ,,,,,, The SRP48 functional employed in most of those studies has additionally been proven to be transferable to other surfaces beyond Cu(111), such as Cu(100) , or Ag(111) . It was also successfully applied to stepped surfaces, including H 2 /Cu­(211) systems. ,,, Another, more recently introduced functional that also shows good agreement with experiments is optPBE-vdW .…”

“…Reactive hydrogen chemistry at surfaces plays an important role in key heterogeneous catalysis processes such as the Haber–Bosch process , or methanol synthesis. − Copper is a particularly interesting metal to study in this context due to its widespread use as a catalyst in many chemical reactions. Consequently, the dissociation of hydrogen on Cu surfaces has become a benchmark problem for experimental − and theoretical − research.…”

“…Numbers inside the circles refer to the respective iteration, with "0" representing the initial model. Both figures include QCD-BOSS reference data, depicted as red triangles (△), reported by Smits and Somers 33.…”