Pseudopotential methods in condensed matter applications

Alkali-metal-affected adsorption of molecules on metal surfaces

Ab initio lattice dynamics of metal surfaces

We have studied the geometrical structure of the Pt(110) surface using medium-energy ion scattering. We find that the structure of the reconstructed (1\ifmmode\times\else\texttimes\fi{}2) unit cell corresponds to a missing-row model with, in contrast to previous reports, a large contraction of the first interlayer spacing, and a buckling of the third layer. The model, which includes deep distortions, is very similar to the one recently established for Au(110)-(1\ifmmode\times\else\texttimes\fi{}2). In addition, we have observed the CO-induced (1\ifmmode\times\else\texttimes\fi{}1) phase, and find that it is well described as a disordered surface.

Structural analysis of the Pt(110)-( 1×2 ) surface using medium-energy ion scattering

From an analysis of the low‐energy electron diffraction (LEED) intensities we have determined the oscillatory distortion of the topmost interlayer spacings of the clean and the (2×1)H covered Pd(110) surface as well as the exact adsorption geometry in this latter structure, which is formed at T<180 K at a coverage of θH≤1.0. An R‐factor analysis was used for quantitative comparison with the experimental data. The oscillatory distortion of the clean surface— d12=−5.1±1.5%, d23=+2.9±1.5%, d34 at its bulk value of 1.37 A (with R factors RP=0.22 , RZJ=0.14 )— is found to be reduced by the H adlayer to d12=−2.2±1.5%, d23=+2.9±1.5%, and d34=bulk value. The H atoms are adsorbed on quasi‐threefold sites with equal distances of 2.0±0.1 A to the two nearest Pd neighbors in the topmost and the closest Pd atom in the second layer, leading to an effective radius of the H atom of rH=0.6±0.1 A. The long‐bridge adsorption site, (octahedral) subsurface sites, or a hydrogen induced reconstruction via a lateral displacement...

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LEED structure analysis of the clean and (2×1)H covered Pd(110) surface

The surface-phonon dispersion curves of Al(110) have been calculated with force constants determined from first-principles self-consistent total-energy calculations. Relaxation of the surface layers produces changes in the surface force constants which have a significant influence on the surface-phonon frequencies near the zone boundary.

K. P. Bohnen

Papers

First-principles calculation of surface phonons on the Al(110) surface.