Ab Initio Molecular Dynamics Simulations of the Adsorption of H₂ on Palladium Surfaces

Abstract

The interaction of hydrogen with palladium surfaces represents a model system for the study of the adsorption and absorption at metal surfaces. Theoretical gas-surface dynamics studies have usually concentrated on the adsorption dynamics on clean surfaces. Only recently has it become possible, based on advances in electronic structure codes and improvements in computer power, to address the much more complex problem of the adsorption dynamics on precovered surfaces. Herein, recent ab initio molecular dynamics studies are discussed that address the adsorption dynamics of hydrogen molecules on hydrogen- and sulfur-precovered Pd surfaces. In addition, the relaxation dynamics of the hydrogen atoms after the dissociation on clean Pd(100) are presented.

Ab initio molecular dynamics calculations on scattering of hyperthermal H atoms from Cu(111) and Au(111)

“…In the AIMD method [71][72][73][85][86][87][88] used here, dynamical quantities are computed using classical Born-Oppenheimer dynamics for nuclear motion while computing the forces on the fly using DFT. The Cu (Au) substrate was modeled using 4 layers as in the static surface calculations discussed above.…”

“…To arrive at the required accuracy, we use AIMD, [71][72][73] which may be considered as the "gold standard" of high dimensional ab initio scattering simulations that can be performed within the framework of classical mechanics. The use of the AIMD method circumvents the need to perform high-dimensional potential fits that capture the coupling of the H-atom translational motion with the surface phonons, as forces are calculated on the fly directly from DFT.…”

Ready, Set and no Action: A Static Perspective on Potential Energy Surfaces commonly used in Gas-Surface Dynamics

“…Nevertheless, the huge number of trajectories required to properly determine small reaction probabilities of e.g. ≤≈ 1% [15] practically excludes direct application of AIMD for many systems for some time still to come. This is particularly true when taking into account nuclear quantum effects, which can be significant for the aforementioned prototypical H 2 adsorbates [8,16].…”

Modified Shepard interpolation of gas-surface potential energy surfaces with strict plane group symmetry and translational periodicity

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] This importance has given rise to a long history of modelling and calculating gas-surface interaction energies, and developing compact representations of these energies. [15][16][17][18][19][20][21][22][23][24][25][26][27] In the Born-Oppenheimer approximation, the energy of a gas phase molecule or adsorbate interacting with a solid surface is dependent only on the positions of the atoms and forms a single valued potential energy surface (PES). Electronic structure theory methods such as periodic density functional theory (DFT) can be used to calculate the value of the PES at any particular gas-surface geometry.…”

“…For interactions with metal surfaces, the DFT approach has been quite successful. [14][15][16][17][18][19]28 Interactions with non-metallic crystal surfaces are harder to describe with DFT, though recent developments with molecular fragmentation descriptions of adsorbates interacting with wide band gap materials show promise. 29,30 Even when one has an electronic structure theory method that can calculate gas-surface interaction energies suitably accurately at discrete points, for dynamics calculations, a continuous representation of the PES is usually required.…”