Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9594808 | Surface Science | 2005 | 9 Pages |
Abstract
We have calculated the dispersion curves of H vibrational modes on Pt(1Â 1Â 1), using first-principles, total energy calculations based on a mixed-basis set and norm-conserving pseudopotentials. Linear response theory and the harmonic approximation are invoked. For 1Â ML coverage with H atoms in the fcc hollow sites, we find modes at 73.5Â meV and 142.6Â meV, polarized, respectively, parallel and perpendicular to the surface, at the Î point of the surface Brillouin zone. The degeneracy of the parallel mode is lifted at the zone boundaries, yielding modes at 69.6Â meV and 86.3Â meV, at the M point, and at 79.4Â meV and 80.8Â meV, at the K point. The changes in Pt surface force constant on H adsorption are found to shift the frequencies of the substrate surface modes from their calculated values for clean Pt(1Â 1Â 1). We also consider the case of subsurface adsorption for 2Â ML of H and present vibrational frequencies of H atoms adsorbed in several subsurface sites. The appearance of new vertically polarized H modes in the range 98-106Â meV (octahedral site occupancy) and 124-162Â meV (tetrahedral site occupancy) is discussed in the context of experimental data.
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Physical Sciences and Engineering
Chemistry
Physical and Theoretical Chemistry
Authors
Sampyo Hong, Talat S. Rahman, Rolf Heid, Klaus Peter Bohnen,