Electronic friction coefficients from the atom-in-jellium model for Z=1−92Z=1-92

The break-down of the Born-Oppenheimer approximation is an important topic in chemical dynamics on metal surfaces. In this context, the most frequently used "work-horse" is electronic friction theory, commonly relying on friction coefficients obtained from density functional theory (DFT) calculations from the early 80s based on the atom-in-jellium model. However, results are only available for a limited set of jellium densities and elements ($Z=1-18$). In this work, these calculations are revisited by investigating the corresponding friction coefficients for the entire periodic table ($Z=1-92$). Furthermore, friction coefficients obtained by including the electron density gradient on the Generalized Gradient Approximation (GGA) level are presented. Finally, we show that spin polarization and relativistic effects can have sizeable effects on these friction coefficients for some elements.Comment: 30 pages, 10 figues, accepted at Physical Review

Highly efficient activation of HCl dissociation on Au(111) via rotational preexcitation

NWOTheoretical Chemistr

Accurate simulations of the reaction of H\u2082 on a curved Pt crystal through machine learning

[Image: see text] Theoretical studies on molecule–metal surface reactions have so far been limited to small surface unit cells due to computational costs. Here, for the first time molecular dynamics simulations on very large surface unit cells at the level of density functional theory are performed, allowing a direct comparison to experiments performed on a curved crystal. Specifically, the reaction of D(2) on a curved Pt crystal is investigated with a neural network potential (NNP). The developed NNP is also accurate for surface unit cells considerably larger than those that have been included in the training data, allowing dynamical simulations on very large surface unit cells that otherwise would have been intractable. Important and complex aspects of the reaction mechanism are discovered such as diffusion and a shadow effect of the step. Furthermore, conclusions from simulations on smaller surface unit cells cannot always be transfered to larger surface unit cells, limiting the applicability of theoretical studies of smaller surface unit cells to heterogeneous catalysts with small defect densities

Atoms in jellium revisited - Implications for electronic friction?

Resumen del póster presentado al CECAM workshop “Challenges in reaction dynamics of gas-surface interactions and methodological advances in dissipative and non-adiabatic processes”, celebrado en Albi (Francia) del 26 al 29 de junio de 2017.Dynamics of atoms and molecules at metal surfaces are of fundamental importance for heterogeneous catalysis and electrocatalysis and thus the sustainable production of energy and fuels. Over the last twenty years there has been more and more evidence that the Born-Oppenheimer approximation (BOA), i.e. one of the most important approximations in theoretical chemistry, is not reliable in this case. How to include the non-adiabatic energy loss due to excitation of electronhole pairs in the metal has thus become an important topic in chemical dynamics on metal surfaces. Electronic friction theory using friction coefficients from an atoms-in-jellium model have become a very important and successful approach. This is commonly referred to as local density friction approximation (LDFA), and has only recently been extended beyond the originally implied independent atom approximation. In both cases, the friction coefficients originate from density functional theory (DFT) calculation for the atoms-in-jellium model from the early 80s. In this work, these calculations are revisited by implementing the atoms-in-jellium model on top of a state-of-the-art atomic solver and using numerical techniques and algorithms which have been developed during the last 25 years. This new implementation (“LDFAtom”) enables calculations at higher numerical accuracy, simultaneously for both total energies and friction coefficients based on less approximate parameterizations of the local density approximation to DFT. This includes atoms and a regime of jellium densities which were not accessible in earlier work and are (now) interesting for dynamics on metal surfaces. Additionally, it also allows to account for unpaired electrons by using spin-polarized DFT. A comparison to the immersion energies and friction coefficients obtained previously (from non-spin-polarized calculations) reveals that these benefit from error cancellation effects and thus are generally reliable. This does not hold for results from spin-polarized atoms-injellium calculations published (for only a few atoms) before. Finally, a thorough analysis including a decomposition into contributions from different angular momenta offers further insights into how spin-polarization can affect both total energies and friction coefficients for several second-row elements.Peer reviewe

Electronic friction coefficients from the atom-in-jellium model for Z = 1–92

The breakdown of the Born-Oppenheimer approximation is an important topic in chemical dynamics on metal surfaces. In this context, the most frequently used work horse is electronic friction theory, commonly relying on friction coefficients obtained from density-functional theory calculations from the early '80s based on the atom-in-jellium model. However, results are only available for a limited set of jellium densities and elements (Z=1−18). In this paper, these calculations are revisited by investigating the corresponding friction coefficients for the entire periodic table (Z=1−92). Furthermore, friction coefficients obtained by including the electron density gradient on the generalized gradient approximation level are presented. Finally, we show that spin polarization and relativistic effects can have sizable effects on these friction coefficients for some elements.N.G. is grateful for his research stay in San Sebastian that has been cofunded by the Erasmus+ programme of the European Union. J.M. acknowledges financial support from the Netherlands Organisation for Scientific Research (NWO) under VIDI Grant No. 723.014.009. J.I.J. acknowledges financial support by the Gobierno Vasco-UPV/EHU Project No. IT1246-19, and the Spanish Ministerio de Ciencia e Innovación [Grant No. PID2019-107396GBI00/AEI/10.13039/501100011033].Peer reviewe

Accurate Reaction Probabilities for Translational Energies on Both Sides of the Barrier of Dissociative Chemisorption on Metal Surfaces

Molecular dynamics simulations are essential for a better understanding of dissociative chemisorption on metal surfaces, which is often the rate-controlling step in heterogeneous and plasma catalysis. The workhorse quasi-classical trajectory approach ubiquitous in molecular dynamics is able to accurately predict reactivity only for high translational and low vibrational energies. In contrast, catalytically relevant conditions generally involve low translational and elevated vibrational energies. Existing quantum dynamics approaches are intractable or approximate as a result of the large number of degrees of freedom present in molecule–metal surface reactions. Here, we extend a ring polymer molecular dynamics approach to fully include, for the first time, the degrees of freedom of a moving metal surface. With this approach, experimental sticking probabilities for the dissociative chemisorption of methane on Pt(111) are reproduced for a large range of translational and vibrational energies by including nuclear quantum effects and employing full-dimensional simulations

Accurate Reaction Probabilities for Translational Energies on Both Sides of the Barrier of Dissociative Chemisorption on Metal Surfaces

Molecular dynamics simulations are essential for a better understanding of dissociative chemisorption on metal surfaces, which is often the rate-controlling step in heterogeneous and plasma catalysis. The workhorse quasi-classical trajectory approach ubiquitous in molecular dynamics is able to accurately predict reactivity only for high translational and low vibrational energies. In contrast, catalytically relevant conditions generally involve low translational and elevated vibrational energies. Existing quantum dynamics approaches are intractable or approximate as a result of the large number of degrees of freedom present in molecule–metal surface reactions. Here, we extend a ring polymer molecular dynamics approach to fully include, for the first time, the degrees of freedom of a moving metal surface. With this approach, experimental sticking probabilities for the dissociative chemisorption of methane on Pt(111) are reproduced for a large range of translational and vibrational energies by including nuclear quantum effects and employing full-dimensional simulations