Lattice vibrations and stability of reconstructed (110) noble metal surfaces

The interplay between the surface phonons and different missing-row reconstructions of (110) noble-metal surfaces is investigated. The phonon dispersion curves and densities of states are calculated for a slab model with 24 layers of atoms, using the Sutton-Chen many-body potential. The phonon contribution to the surface free energy is evaluated for Au, Pt and Ag surfaces. The results show that surface phonons play an important role in stabilizing a surface reconstruction when the energy difference between different reconstructions is of the order 1 meV/(surface unit cell) or smaller, and in particular in the case of Au(110) when the (1 x 2) and (1 x 3) reconstructions are close in energy. We also observe that the Sutton-Chen potential reproduces the phonon dispersion curves better for Ag (4d metal) than for Au and Pt (5d metal). (C) 1999 Elsevier Science B.V. All rights reserved.