Non-contact AFM images of a C60 molecule adsorbed on the Si(0 0 1) surface: An ab initio method

A theoretical non-contact atomic force microscope (nc-AFM) image is simulated for an individual C60 molecule adsorbed on the clean Si(0 0 1) surface. The ability to identify the intramolecular features of the molecule though nc-AFM imaging would allow many of the different configurations the molecule may take when adsorbed, to be identified. This would be an important preliminary step in the manipulation of the molecule along the surface, as the initial configuration that the molecule is in will affect the periodicity of the tip trajectory during the manipulation event (see D.L. Keeling et al., Phys. Rev. Lett. 94 (2005) #146104). Presented in this paper are simulated images and force curves above important sites for key stable configurations of the C60 molecule. It is shown that in principle it is possible to distinguish between the different configurations of the molecule using nc-AFM. An ab initio DFT method was used to accurately describe the chemical interaction between the adsorbate and the Si tip, which has a single dangling bond at its apex.