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The stability of fcc (1 1 1) metal surfaces |
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| Authors: | TM Trimble RC Cammarata K Sieradzki |
| Institution: | a Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD 21218, USA b Department of Physics and Astronomy, University of Maryland, College Park, MD 29742, USA c Department of Mechanical and Aerospace Engineering, Arizona State University, P.O. Box 876106, Tempe, AZ 85287, USA |
| Abstract: | The results of a theoretical study on the stability of fcc (1 1 1) metal surfaces to certain commensurate-incommensurate reconstructive phase transformations is presented. Specifically, we have performed computer simulation studies of the 22×√3 surface reconstruction of Au(1 1 1). This reconstruction involves a uniaxial contraction of the top monolayer corresponding to a surface strain of about 4.3% and has been observed to be the stable structure for the clean surface at low temperatures. The driving force for the reconstruction has been associated with the quantity (f−γ), where f is the surface stress and γ is the surface free energy, while the opposing force is due to the disregistry with the underlying lattice. A continuum model yields a stability criterion that depends on the knowledge of a small number of physical quantities: f, γ, the equilibrium nearest-neighbor spacing r1 and the shear modulus G. We have performed molecular dynamics simulations as a general stability analysis of these types of reconstructions. The results are in excellent agreement with the continuum model. The simulations using embedded-atom method potentials also accurately reproduce many observed features of the reconstruction on Au(1 1 1). |
| Keywords: | Surface relaxation and reconstruction Surface stress Surface energy Gold Molecular dynamics Metallic surfaces Low index single crystal surfaces |
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