Theoretical computation of the phononic vibrational dynamics of Au3Pd, AuPd, and AuPd3 nanostructures at the [AunPdm]/Au(110) bimetallic ordered surface alloy systems

Abstract

In this work we develop a calculation for the surface phononic dynamical properties of the three ordered bimetallic surface alloy nanostructures [AunPdm]/Au(110) where [AunPdm] = Au3Pd, AuPd, and AuPd3, for the appropriate concentrations of palladium atoms in the proportions 25 %, 50 %, and 75 %, respectively, at the surface boundaries. They are ordered equilibrium structures, which have been characterized, by Atanasov and Hou (2009). Using the phase field matching theory (PFMT), and the Green's function formalism, the surface phonon dispersion curves are computed, in the harmonic approximation, along the high-symmetry directions ΓX, XS, SY and YΓ of the Brillouin zone of the corresponding surface alloy nanostructure. The local vibration densities of states (LDOS) are also calculated for these systems. The results reveal that the number and the dynamic behavior of the surface phonon and resonance modes, are very sensitive to the concentration of the palladium adsorbate atoms in the [AunPdm] nanostructures. The number and characteristics of these modes are modified at the surface and shifted to higher energies as the concentration increases. These phononic results can greatly contribute to our understanding of the dynamic effects underlying potential technological applications of these surface alloy nanostructures.