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O: Oberflächenphysik

O 25: Methodisches

O 25.2: Talk

Wednesday, March 29, 2000, 14:45–15:00, H45

The Role of Atomic Relaxation and of the xc Functional in the Calculation of the Surface Stress Tensor — •Weixue Li, Frank Wagner, and Matthias Scheffler — Fritz-Haber-Institut der MPG, Berlin,Germany

Recently the investigation of the surface stress and its influence on the adsorption of atoms and molecules as well as its role as driving force for surface reconstructions has been of considerable interest. Using first-principle calculations, the stress is typically calculated by a numerical derivative of the surface energy as function of the in-plane strain [1,2]. Usually the surface geometries have been relaxed for zero strain, and the strain-induced relaxation of the interlayer spacing as well as the contribution from the strained “bulk layers” of the slab to the stress has not been discussed so far, since it was believed to be neglegible.

To check these assumptions we performed density-functional theory for the example of the Pt(100)-surface. Our results show that in general the relaxation of the strained slabs has a noticeable influence on the derivative of the surface energy at zero strain. We will also show, that the change of interlayer spacing is described well by the Poisson effect of the bulk system. The contribution of the strained “bulk layers” must be considered properly to get physical meaningful results.

[1]   M. Bockstedte, et al., Comput. Phys. Commun. 107, 187-222 (1997) ; P. Blaha, K.Schwarz, P. Sorantin, and S. B. Trickey, Comput. Phys. Commun. 59 (1990) 399.