Modelling the manipulation of C60 on the Si(001) surface performed with NC-AFM

Abstract

We present a theoretical model of manipulation of theC60 molecule on the Si(001) surface with a non-contact atomic force microscope(NC-AFM). The model relies on the lowering of the energy barrier for theC60 manipulation due tothe interaction of the C60 with an AFM tip and the subsequent thermal movement of the molecule over this barrier. Weperformed numerical simulations of these energy barriers for a series of tip positions relative tothe molecule to show how the barriers change with the tip position. The values of thesebarriers are then used in kinetic Monte Carlo simulations to estimate the probability of theC60 movement for different tip positions and temperatures. Virtual atomic forcemicroscope simulations, which include the kinetic Monte Carlo treatment of theC60 movement, are then performed to describe in real time the process of movement of theC60 molecule during an NC-AFM scan. Our results demonstrate that manipulation of theC60 molecule, which is covalently bound to the surface, is possible with NC-AFM, even though thereis no continuous tip–molecule contact, which is known to be a necessary requirement for theC60 manipulation with scanning tunnelling microscopy. We show that the manipulation eventcan be identified in real NC-AFM experiments as an abrupt change in the distance of thetip closest approach (topography), and as spikes in the frequency shift and dissipationsignals.