Molecular Dynamics Simulations of Dynamic Force Microscopy: Applications to the Si(111)-7x7 Surface

摘要

Molecular dynamics simulations have been performed to understand true atomicresolution, which has been observed on the Si(111)-7$\times$7 surface bydynamic force microscopy in ultra high vacuum(UHV). Stable atomic-scalecontrast is reproduced in simulations at constant mean height above a criticaltip-sample separation when monitoring the interaction force between tip andsample. Missing or additional adatoms can be recognized in such scans, althoughthey are less well resolved than native adatoms. The resonance frequency shift,as well as arbitrary scans, e.g. at constant force can be computed from aseries of force-distance characteristics. By means of dynamic simulations weshow how energy losses induced by interaction with an oscillating tip can bemonitored and that they occur even in the non-contact range.