Theoretical study of atomic hydrogen adsorbed on Pt (111)
Abstract
The structural and electronic properties, including the surface stress, of adsorbed hydrogen on Pt (111) were studied by means of density-functional theory (DFT) together with the full-potential linear-augmented-plane-wave (FP-LAPW) method considering three different coverages: Θ= 0.33, 0.66, and 1.0. We find that the fcc position is always energetically favored compared to the hcp position. The structural relaxations of the two adsorption sites are found to be noticeably different. Particularly for the 1-ML case, for which the smallest energy difference was found, the outwards relaxation of the topmost layer amounts to 2.5 % for fcc- and 3.5 % for hcp-adsorption. This reflects a general trend: The hcp- compared to the fcc-adsorption is characterized by a stronger outward relaxation of the first surface layer and a interlayer rearrangement of the atoms which elongate the interatomic bonds between first and second surface layer. Our calculations show that the H-adsorption releases the tensile surface stress. Especially for the 1-ML coverage we find a significant deviation for fcc- and hcp-adsorption: Whereas the surface stress is tensile for the hcp-adsorption, it is compressive for the fcc-adsorption. For other coverages the differences are less pronounced, but we always find a stronger reduction of the surface stress for the fcc-adsorption. ^*Present address: Universitá di Cagliari, I-09124 Cagliari, Italy
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2000
- Bibcode:
- 2000APS..MAR.A9006P