The surface energy (γ) and surface stress (τ) for semi-infinite close-packed surfaces of 4d transition metals have been calculated using ab initio total-energy methods. The moderate agreement between the present and former theoretical data for τ indicates the high level of numerical difficulty associated with such calculations. For the most close-packed surfaces, the present unrelaxed τ values follow the typical trend characteristic for the cohesive energy in nonmagnetic transition-metal series, whereas the relaxed τ values group around ∼1mJ/m2, obtained for Y, Zr, and Ag, and ∼3mJ/m2, calculated for Nb, Mo, Tc, Ru, Rh, and Pd. We have found that the average surface energy reduction upon layer relaxation is around 4%. At the same time, a large part of the surface stress is released during the surface relaxation process. To explain the observed behaviors, we have established a simple relationship, which connects the variations of γ and τ to the layer relaxation. This relation reveals the principal factors determining the difference between the surface energy and stress release rates at 4d transition-metal surfaces.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Dec 15 2005|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics