MODELING OF SURFACES OF CONSTANT FORCE ABOVE A LATTICE OF CLOSE-PACKED ATOMS IN THE REPULSIVE MODE

Surfaces of constant force (force contours) are calculated for the sca nning of an AFM tip over a lattice of close-packed atoms in the repuls ive mode. It is shown that discontinuities are observed on the force c ontours in the regions between the atoms of the surface lattice for su fficiently small initial scanning hieghts of a tip with a single atom at its end. A cluster model of the tip end, which ensures continuity o f the scanning at arbitrary initial heights, is constructed. The depen dence of the AFM images on the orientation of the cluster on the tip e nd relative to the crystallographic axes of the surface is intestigate d for both an unperturbed lattice of close-packed atoms and a lattice containing point defects. The diagnostic possibilities of the findings are discussed.