Adsorbed nano-meter scale species are markedly influenced by weak local interaction including strain. Stability of nano-scale construction on the surface is crucially influenced by such weak interaction but the direct observation by ordinary experimental method is difficult. Scanning electron microscopy (STM) provides not only high resolution in real space but also direct information about the interactions and the strain or stress. As discussed in this paper, the weak interaction directly influences on such phenomena as the formation and the array of unusual nano-size material named quasi-compound, stability of the nano-scale reconstruction, instability of the phase boundary, and array of the binary molecules. It is also shown that the selection of reaction sites is influenced by the weak interaction for coming in molecules, and it is deduced that such weak interaction may relate to the pre-exponential factor (σ) of σe^−ε/kT. Taking these facts into account, we could say that it is difficult to predict highly active and highly selective catalyst by potential energy calculation because specific nature of heterogeneous catalysis depends on the σ.