CPM Seminar
Quantum delocalization of hydrogen atoms and dissociative
hydrogen adsorption on palladium
Seong-Gon Kim
Department of Physics and Astronomy
Mississippi State
University
The quantum delocalization of hydrogen atoms near the hydrogen atom
vacancies on a palladium (111) surface is studied using density
functional theory (DFT). Our quantum delocalization model elucidates
the puzzle presented by a recent experiment [T.~Mitsui, et al,
Nature 422, 705 (2003)]. In this experiment, Salmeron and his
coworkers reported, contrary to conventional belief, that
two-vacancy sites are inactive and that aggregates of three or more
hydrogen vacancies are required for efficient hydrogen molecule
dissociation and adsorption on a palladium (111) surface. Our total
energy calculation shows that one or two hydrogen atoms delocalized
over three available adsorption sites are energetically more stable
than the conventional model of hydrogen vacancies where hydrogen
atoms are localized in the fcc adsoption sites. We found that
delocalized vacancies provide a very compelling mechanism to explain
the ineffectiveness of two-vacancy sites. We also generate simulated
STM images of various types of vacancies that provide clear
interpretation of experimentally observed STM images.
Thursday, November 18th 2004, 15:30
Ernest Rutherford Physics Building, R.E. Bell Conference Room (room 103)
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