A model for the physical adsorption of atomic hydrogen

Abstract

The formation of the holding potential of physical adsorption is studied with a model in which a hydrogen atom interacts with a perfectly imaging substrate bounded by a sharp planar surface; the exclusion of the atomic electron from the substrate is an important boundary condition in the model. The interaction energy and the dipole and quadrupole moments of the ground state are determined with a variational calculation. The polarizability tensor of the ground state and the interaction energies in the first few excited states are also determined. A quantitative analysis is given of the transition to the dispersion-force, large-separation regime using results of perturbation theory and of the variational solution for the ground state of a hydrogen atom in the presence of a nonimaging wall. The relation of results for the image model to ideas used in the modelling of experiments is discussed; this includes a treatment of image field contributions to the depolarizing field at an adatom.

Interaction between atoms and surfaces: A bond-pair description based on an extended Anderson model

“…Distances are measured with reference to the first plane of substrate atoms. The comparison with other existing results in the literature [9][10][11]13,54 shows that after adding the image potential term to the calculated HF level shifts, good agreement is Ref. 11.…”

Variational calculations in a halfspace for the interaction of a ground and excited state helium atom with its mirror image

“…(5) as well as a smooth switching for large values of z~ and of z2 leading to a free helium atom. We shall see below that the results obtained for the hydrogen atom are in good agreement with those of Bruch et al [9], and this validates our guess for the functional form off(z). The function 0 = (P" f2 obtained is interesting due to its analytical simplicity and because of its simple dependence upon the inter-electronic distance r~.2 through f2 Eq.…”

“…2. One can observe that they follow the well known asymptotic behavior: E=-1/4d 3, resulting from coherent dipoledipole interactions, and are in good agreement with those obtained by Bruch et al [9]. This is gratifying since the trial function ~ Eq.…”

“…This choice is discussed by Bruch et al [9]; it looks to be a little bit arbitrary, but nevertheless it leads to good results for helium atom as we show below. It allows also a check of our trim wave functions with those of the previous authors.…”

“…To do so, we have extended to an helium atom a model proposed some years ago by Bruch et al [9] for the hydrogen atom interacting with a perfectly imaging metallic conductor limited by a plane surface. In this approach short range forces are accounted by means of boundary conditions which correspond to the exclusion of the electrons of the adsorbate atom from the solid surface.…”