Density functional study of the adsorption of a C_60 monolayer on noble metal (111) surfaces
Abstract
Large-scale density functional calculations have been applied to investigate thoroughly the energetics and electronic structure of a C_60 monolayer adsorbed on noble metal (Cu, Ag and Au) (111) surfaces. Various molecular orientations and adsorption sites have been examined. We find that the most energetically preferred adsorption configuration corresponds to a hexagon of C_60 aligned parallel to the surface and centered on an hcp site on all noble metal (111) surfaces. Analysis of the electron density difference and density of states indicates that the interaction between C_60 and the noble metal surfaces is primarily covalent, with some ionic character (charge transfer). This picture is in contrast with the common notion developed from experiments that the interaction between C_60 and noble metal surfaces is mostly ionic. We also find that the work function decreases by 0.09 eV on Cu(111) surface, increases by 0.1 eV on Ag(111) surface and decreases by 0.6 eV on Au(111) surface upon adsorption of a C_60 monolayer, in good agreement with the experimental data. The opposite change of the work function on the noble metal surfaces is explained well by examining the multiple dipole formation at the interface. This work has been supported by DOE/Basic Energy Science/Computational Material Science under contract number DE-FG02-97ER45660.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARH17003W