The Effects of Lattice Motion on Eley-Rideal and Hot Atom Reactions:  Quasiclassical Studies of Hydrogen Recombination on Ni(100)

Abstract

Quasiclassical methods are used to simulate the interactions of H or D atom beams with D- or H-covered Ni(100) surfaces. The Ni substrate is treated as a multilayer slab, and the Ni atoms are allowed to move. The model potential energy surface is fit to the results of detailed total-energy calculations based on density functional theory. Most of the incident atoms trap to form hot atoms, which can eventually react with an adsorbate, or dissipate their energy and stick. The incident atom is found to lose several tenths of an eV of energy into the metal, upon initially colliding with the surface. This limits reflection to a few percent, at all coverages, and secondary reactions between adsorbates are significantly lowered. Long time hot atom reactions are also found to be damped out by the inclusion of lattice motion, leading to increased sticking, even at high coverages where dissipation into the adsorbates should be the primary energy loss mechanism. Overall, the inclusion of lattice motion is found to improve agreement with experiment.

Attenuation of hydrogen radicals traveling under flowing gas conditions through tubes of different materials

“…Calculations indicate that the sticking coefficient of atomic hydrogen on catalytic metal surfaces such as Ni͑100͒ is nearly unity at all hydrogen coverages. 33 Experiments are also consistent with hydrogen sticking coefficients close to unity on bare Ni͑111͒ ͑Ref. 34͒ and Ni͑110͒.…”

Dynamics of H2 Eley-Rideal abstraction from W(110): Sensitivity to the representation of the molecule-surface potential

“…[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Results of classical trajectory calculations have been found in reasonable agreement with those of quantum scattering simulations for ER abstraction involving hydrogen atoms in reduced dimension models. 12,13,20,23,[25][26][27][28][29][30][31][32][33][34][35][36] Early dynamical studies of the H+H/W ER process made use of twodimensional (2D) model potential energy surfaces (PES), depending on the altitude of the molecule above the surface and the H-H distance, representing only a collinear geometry where the projectile impinges on top of the target atom.…”

“…Unfortunately, the very small cross sections of the H+H ER process on metal surfaces (<1 Å 2 ) 12,14,20,21,25,[43][44][45][46] hamper the use of Ab Initio Molecular Dynamics (AIMD) simulations [47][48][49][50][51] that circumvent the errors of any PESparametrization method. Therefore, studies of the sensitivity to the PES parametrization of the ER dynamics are desirable.…”

“…One of the PESs (hereafter referred to as FPLEPS) is a result of a global analytical fitting 52, 53 using a generalization [54][55][56] of the LondonEyring-Polanyi-Sato (LEPS) function [57][58][59] widely used in the past to investigate H+H ER abstraction processes on metal surfaces. 12,14,20,21,25,43,44,46 The other PES (hereafter referred to as CRP) has been obtained by interpolation using the corrugation reducing procedure 60 which has been widely used 42,49,[60][61][62][63][64][65][66][67][68][69][70][71][72][73][74] and successfully gauged against AIMD results 49,75 of dissociative adsorption probabilities but scarcely used to investigate ER abstraction processes. It has to be mentioned that CRP has already been used in the context of recombination process but for modeling the LangmuirHinshelwood mechanism (LH), 76 which can be seen as the reverse mechanism of dissociative adsorption.…”

Communication: Hot-atom abstraction dynamics of hydrogen from tungsten surfaces: The role of surface structure

“…Dissipation has been found to quantitatively affect N 2 reactivity but only marginally that of H 2 . 37 Though extended knowledge has been gathered on ER abstraction, pioneering molecular dynamics simulations [38][39][40] and comparisons between kinetics experiments and models 18,38,41,42 have suggested hydrogen abstraction to essentially proceed via the HA process for various metals. Recent theoretical works have thus focused on this issue, in particular for H 2 recombining from W(110).…”