Energies of steps, kinks, and defects on Ag{100} and Ag{111} using the embedded atom method, and some consequences

• Published in: Surface science 1993-10, Vol.295 (3), p.462-484
• Main Authors: Nelson, R.C., Einstein, T.L., Khare, S.V., Rous, P.J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Composition; defects and impurities; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Metals. Metallurgy; Physics; Solid surfaces and solid-solid interfaces; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(93)90293-S

Using the embedded atom method (EAM) we compute the energies of principal steps, kinks, and single-layer clusters of adatoms (islands) and of vacancies for Ag{100} and Ag{111}. The energies are semiquantitatively consistent with experiments. Comparisons are frequently made with estimates based on nearest-neighbor bond counting. On Ag{111} and Pt{111} the ratio of the energies of the two close-packed steps is closer to unity than measured in experiments on Pt. The energies of clusters are essentially proportional to their perimeter, providing an easy way to estimate the binding energy of clusters to step edges. Adatom-vacancy symmetry is a good approximation except for single-site defects. Our calculations of barriers for single-atom diffusion near steps, compared to across terraces, are consistent with the fractal-like fingered growth of islands experimentally observed on {111} but not seen on {100}. Computed spring constants of surface atoms suggest small changes in perpendicular vibration frequencies near step edges.