Eley–Rideal and hot atom reactions between hydrogen atoms on Ni(100): Electronic structure and quasiclassical studies

Abstract

The reactions of gas-phase H (or D) atoms with D (or H) atoms adsorbed onto a Ni(100) surface are studied. Electronic structure calculations based on density functional theory are used to examine the interaction of H atoms with the Ni(100) surface, as well as the interactions between two H atoms near the metal surface. A model potential-energy surface based on ideas from effective medium theory is fit to the results of these electronic structure calculations. Quasiclassical trajectory methods are used to simulate the interaction of low energy H and D atom beams with H and D-covered Ni(100) surfaces. It is found that hot-atom processes dominate the formation of molecular hydrogen. The distribution of energy in the product molecules is examined with regard to the various pathways available for reaction. The initial adsorbate coverage is varied and is shown to control the relative amounts of reflection, reaction, sticking, and subsurface penetration. Our results are compared with those from similar studies on Cu(111) and available experimental data for Ni(100).

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. 11,37 More recently, Rutigliano and Cacciatore 38 investigated the ER abstraction process for H+H/W(100) by using a tight binding approximation for the PES 39,40 that allowed them to consider explicitly not only the six degrees of freedom of the H 2 but also the dynamical coupling with tungsten phonons.…”

“…15,78 The initial conditions for QCT simulations have been specified as follows: the target, located in the adsorption well, is given initial energies and random initial vibrational phases corresponding to the quasi-classical zero point energy (ZPE) of each normal mode, calculated within the harmonic approximation,. 18,20,26,36 Alternative Wigner distribution in the sampling of the target initial conditions have revealed very little differences from quasi-classical ZPE sampling for the ER recombination of H 2 on graphene. 36 The ZPE for vibrational motion normal to the surface is 71 meV (68 meV) for the CRP (FPLEPS).…”

“…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.…”

“…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.…”

Physisorption energy of successive layers of H2 molecules with a (100) surface of copper

“…To our knowledge, such second layer interaction has not yet been studied for any kind of surface and molecule. In a recent study, Guvenc et al [12] investigated a close but different problem, namely the reactive interaction between one H (or D) atom in the gas phase and one adsorbed H (or D) atom on a Ni(1 0 0) surface. (iii) The last step consists in an estimation of the physisorption energy of a third layer of H 2 molecules.…”