A fully ab initio approach to scanning-tunneling-microscope (STM) images is presented, treating the sample and the tip as a single system. The approach combines density functional theory with the Kubo-Greenwood formalism for the conductivity. The STM images are calculated by taking into account atomic relaxations that occur on both the surface and the tip due to their mutual interactions. Illustrative examples will be presented for the case of a clean Al(110) surface and the same surface with a vacancy, showing that buckling relaxations occur that smooth the STM images, reducing the observable corrugation of the surface.

• Received 29 June 1998

DOI:https://doi.org/10.1103/PhysRevB.59.R5320