Visualization of Thermally Fluctuating Surface Structure in Noncontact Atomic-Force Microscopy and Tip Effects on Fluctuation: Theoretical Study of Si(111)-( √3 ×√3)-Ag Surface
We investigated noncontact atomic-force microscopy (NC-AFM) images of a thermally fluctuating surface structure together with tip effects based on the first-principles electronic state calculation. As an example the Si(111)-( (3)×(3))-Ag ( (3)-Ag) surface is studied. We have succeeded in theoretically visualizing the thermal fluctuation of the (3)-Ag surface at room temperature, and in reproducing the observed NC-AFM image for the first time. Further, the pinning effect of the thermal fluctuation of the (3)-Ag surface by the tip is clarified, which shows a novel ability of NC-AFM to modify the surface structure.