Effects of subsurface Na, H and C on CH sub(3) adsorption on Ni(111)

Ab initio valence orbital configuration interaction calculations are used to study the energy effect of Na, H and C atom subsurface species on CH sub(3) chemisorption at a hollow 3-fold site on Ni(111). The lattice is modeled as an embedded three layer cluster of 41 atoms. Ni3d orbitals are explicit...

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Bibliographic Details
Published in:Surface science 1992-01, Vol.277 (3), p.L95-L99
Main Authors: Yang, Hong, Whitten, Jerry L, Thomas, Raymond E, Rudder, Ronald A, Markunas, Robert J
Format: Article
Language:English
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Summary:Ab initio valence orbital configuration interaction calculations are used to study the energy effect of Na, H and C atom subsurface species on CH sub(3) chemisorption at a hollow 3-fold site on Ni(111). The lattice is modeled as an embedded three layer cluster of 41 atoms. Ni3d orbitals are explicitly included on seven nickel atoms on the surface. The calculated chemisorption energies of pyramidal CH sub(3) on Ni(111) are 38 for the clean surface and 50, 47, and 17 kcal/mol for the Na, H, and C implants, respectively. The energies required to distort tetrahedral CH sub(3) into a planar structure are 22 kcal/mol on clean Ni(111), 30 kcal/mol with the Na implant, 24 kcal/mol with the H implant, and 12 kcal/mol with the C implant, respectively. Thus, Na below the surface may stabilize a carbon overlayer to a tetrahedral diamond structure. CH sub(3)-surface distances, C-H stretching and surface-CH sub(3) vibrational frequencies are also reported.
ISSN:0039-6028