FORCES OF A PT ADATOM ON A PT(100) SURFACE BY THE EMBEDDED-ATOM METHOD

The perpendicular forces acting on Pt adatoms from Pt(100) surfaces ar e presented using the embedded-atom method. The force maps are classif ied into four force regions, When the adatom is very close to the surf ace the force is repulsive (region 1). The most repulsive forces repre sent the corresponding first layer atoms. Contrary to these true atomi c images, when the adatom is near the surface and the force is attract ive (region 2), there is a build up of the least attractive force peak s among the first layer atoms and the positions above the first atoms are surrounded by the four least attractive force peaks. When the forc e is strongly attractive (region 3), stronger attractive forces are no t found directly above the first layer atoms, but are located above th e second layer atoms, When the adatom is far from the surface and the force is weakly attractive (region 4), stronger attractive forces are found above the first layer atoms, In general, the complicated force m aps caused by the many-body interactions appear in the attractive regi ons, which has not been seen in early calculations using pair-wise pot entials.