Surface-diffusion mechanism versus electric field: Pt/Pt(001)

Physical Review B - Condensed Matter and Materials Physics

Volumn 64, Issue 12, 2001, Pages

  Feibelman, Peter J ^a  

^a SANDIA NATIONAL LABORATORIES   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

PLATINUM;

ARTICLE; CALCULATION; DIFFUSION; ELECTRIC FIELD; ELECTRON; ENERGY; MATHEMATICAL ANALYSIS; MICROSCOPY; TEMPERATURE DEPENDENCE;

EID: 0035883520     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.64.125403     Document Type: Article

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32. the Pt(001) and Pt(111) work functions are 5.84 and 5.93 eV. These results are reasonably consistent with a more recent photoemission-threshold value of (formula presented) for Pt(111) [G N. Derry and Z. Ji-Zhong, Phys. Rev. B39, 1940 (1989)].
33. This was inadvertent. On abandoning efforts to converge the electron densities of seven-layer Pt(001) slabs in favor of the more stable five-layer case, I neglected to reduce the width of the periodically repeated cell. I did reduce it, though, to ∼3 Å for calculations with a 1.5-V/Å external field.
34. Here as everywhere in this article, a positive field is defined as a field that pushes electrons into the metal.
35. The ratio of hopping to concerted substitution prefactors should perhaps be taken more seriously, both in the theoretical and experimental analyses. The results in Table I make it clear that as the external field increases from -0.4 to 0.8 V/Å, the energy of the symmetric dimer configuration rises until it is virtually equal to the energy of the concerted substitution barrier. At 0.8 V/Å, the energy hypersurface for concerted substitution is unusually flat in the vicinity of the transition geometry, and one might expect a larger than usual concerted-substitution prefactor. (Note that to compare the energies of symmetric dimer and the transition state for each field strength, subtract the hollow-site binding energy in column 1 of Table I from the symmetric exchange energy in column 3 and compare the result to the substitution barrier energy in column 5.)
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