This Research at Undergraduate Institution grant is awarded for theoretical research on surface reconstruction. Surface reconstruction refers to the spontaneous rearrangement of atoms that occurs in the surface atomic layers of some materials. These rearrangements are of interest sine they represent important opportunities to compare theoretical treatments of surface energetics and experimental probes of the structure of surface layers. Reconstructive surfaces present much more stringent tests of scientific methods than do static surfaces. Two specific systems will be investigated. The (110) surface of gold will be studied where through surface diffusion a reconstructed surface with missing rows of gold is formed. The Embedded Atom Method and Monte Carlo techniques will be used to study the energetics. The (001) surface of tungsten in which each atom is displaced slightly from its equilibrium position in an alternating pattern will also be studied. In this case the energetics related to the surface phase diagram will be examined. %%% The collective properties of atoms on the surfaces of solids are different than those in the bulk due to the absence of other atoms beyond the surface layer. The energetics of surface atoms are thus different than those in the bulk. One of the consequences of this difference in energetics is that the surface atoms can arrange themselves differently than the bulk. These rearranged atoms can result in the surface layer having different physical properties than the bulk solid. For instance, certain surface structures are better than others for catalysis. The proposed research will study two classes of surface reconstruction in two model systems. The results will help to understand why specific surface structures are formed in these materials.
