This project focuses on various aspects of surface processes which have a direct impact on the understanding of atomic details of solid surfaces. This understanding is critical for the correct interpretation of scanning tunneling microscopy (STM) images, and other technical areas such as corrosion protection, sensors, and electronics. One of the goals of this project is to simulate plane wave codes, which provide the density of states only a few Angstroms above the surface of various materials which are currently under experimental investigation. These `simulated' STM images will shed light on the materials that are best suited for STM. A second goal is to simulate surface defects, such as step edges, which are thought to beimportant in chemical processes. The objective is to investigate a hypothesis that a far-ranging electrostatic repulsion can cause certain adsorbates to avoid step edges, as recent experiments show. The mathematical description of these phenomena relies on the modeling of atomic forces acting on the material surface.