ADSORPTION SITE AND STM IMAGE OF O-2 ON PT(111)

We perform a molecular dynamics (MD) study of non-dissociative adsorpt ion of O-2 molecule on Pt{111} surface at low temperatures, and analys e the STM image of the obtained geometry. The interatomic forces for t he simulation are calculated using tight-binding method in density mat rix formalism with the constraint of local charge neutrality. The STM image is constructed by calculating tunneling current between a sharp metal tip and the sample. The MD simulation gives an adsorption site w ith a very plausible bonding behaviour. Furthermore, the corresponding STM image is similar to recent experimental images. The present simul ation suggests formation of a larger complex of the oxygen molecule an d two Pt atoms. It turns out that the STM image does not directly show the orientation of the O-2 molecule, and has such a complicated origi n in interference of atomic orbitals of the formed complex, that an op timization of the surface structure using MD simulation, instead of in tuitive considerations, is necessary. (C) 1998 Elsevier Science B.V. A ll rights reserved.