Phenomenological Analysis of the W(001) Reconstructed Surface
Recently the W(001) reconstructed surface and the effects of adatoms on the reconstruction have been studied intensively. These studies show that the surface displacement modes (the mode and the incommensurate modes around the M point in the 1st Brillouin zone) have instability towards surface reconstruction. By means of a lattice dynamical approach and a symmetry consideration of the system we investigate the eigenvectors of these displacement modes and the energy dispersion, and present the general form of the Ginzburg-Landau (G-L)-type free energy functional describing the reconstructed surface. In the course of this study, we discuss also the Mo(OOl) reconstructed surface. On the W(001) reconstructed surface, the interaction between adatoms and “displaced” surface W atoms might make a major contribution to the adsorbate-induced changes of surface W atom displacements. We examine the effects of this interaction on the commensurate — incommensurate (C-IC) displacive transition, that is, the instability of the C phase towards the IC phase.
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