THEORETICAL-ANALYSIS OF TIP-MGO(100) SURFACE INTERACTIONS

We present a quantum self-consistent calculation of tip/insulating sur face interactions, performed under the assumption of a rigid geometry, intended to be a first step in the study of images recorded in Scanni ng Force Microscopy. The MgO(100) surface is modelled by an embedded c luster and the tip by an MgO cube presenting various orientations: 1) an Mg or O corner on-top the surface, or 2) a face parallel to the sur face. Two cases are considered: a perfectly planar surface and a rough surface with four additional adsorbed atoms. No supercell geometry is assumed which avoids spurious lateral interactions. As a function of the tip geometry and of the force value chosen to image the surface, w e discuss some factors which drive the corrugation and the resolution in an Atomic Force Microscope measurement.