Atomic-scale force-vector fields.

The magnitude and direction of forces acting between individual atoms as a function of their relative position can be described by atomic-scale force-vector fields. We present a noncontact atomic force microscopy based determination of the force fields between an atomically sharp tip and the (001) surface of a KBr crystal in conjunction with atomistic simulations. The direct overlap of experiment and simulation allows identification of the frontmost tip atom and of the surface sublattices. Superposition of vertical and lateral forces reveals the spatial orientation of the interatomic force vectors.