Impact of atomic relaxation on the breaks of constant force surfaces in AFM

A calculation model for determination of the shapes of the constant force surfaces and profiles of lateral forces for the case of the AFM tip scanning the closely packed lattice in contact mode is proposed. Atomic relaxation is taken into account in this model. The existence of breaks on constant force surfaces, which was predicted earlier in an approximation of the fixed lattice, is confirmed. It is shown that due to non-zero atomic mobility, breaks appear for smaller scanning forces than assumed earlier. The shapes of the continuous constant force surfaces and profiles of lateral force components are computed. These results may be used for diagnostics of point defects on the surface.