Corrugation of attractive force and its effect

The effect of the repulsive atomic force in the STM imaging process is well-established experimentally and theoretically. It is natural to inquire about the effect of the corrugation of attractive forces in the STM imaging process (Wintterlin et al., 1989). The problem was studied using a first-principles numerical method by Ciraci, Baratoff, and Batra (1990a). The major conclusions are as follows  

At the operating tip-sample distances of STM, the attractive force prevails. 

The magnitude of the attractive force at the hollow site (//) is larger than that at the top site (J). In other words, there is a reversed corrugation for the attractive force. 

The deformation of the tip would reduce the observed corrugation of the constant-current topographic image. 

For most metals, the effect of deformation on the corrugation in the topographic image is much smaller than the observed values. 

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