I. Yu. Sklyadneva

Vibrational states on vicinal surfaces of Al, Ag, Cu and Pd

We present the calculation of vibrational modes and lattice relaxation for the (110), (211), (311), (511), (331) and (221) surfaces of Al, Ag, Cu and Pd. The surface phonon frequencies and polarizations are obtained for relaxed and unrelaxed surfaces using embedded atom model potentials. On all surfaces studied step-localized vibrational modes and surface states localized on terrace atoms are found. It is shown that as the terrace width increases so does the number of surface phonons. It is found that interlayer relaxation leads to a shift in the frequencies of the surface states and to a change in the number and localization. In particular, it may cause the appearance or disappearance of step modes. It is shown that the character of relaxation on vicinal surfaces is determined by the number of atoms on a terrace. A comparison of the results with the available experimental data for the Al(221), Cu(211), and Cu(511) surfaces indicates that there is a good agreement with the experimental data.

Vibrations on the (110) surface of FCC metals

Abstract We present the calculations of vibrational states on the Al(110), Cu(110), Ag(110) and Pd(110) surfaces. The surface phonon frequencies and polarizations are calculated using embedded atoms potentials. For all surfaces of interest a surface state at the \ gG point, characterized by shear vertical displacements of atoms of the two upper layers is obtained. It is in contradiction to earlier calculations and experimental study for the Al(110) surface and in good agreement with experimental measurements for the Cu(110), Ag(110) and Pd(110) surfaces. It is shown that vibrational spectra of these surfaces are like to each other. On the whole, obtained results are in good agreement with available experimental data and first principles calculation results.

Vibrations on Cu surfaces covered with Ni monolayer

Vibrational modes on the Cu(100) and Cu(111) surfaces covered with a Ni monolayer have been calculated using the embedded-atom method. A detailed discussion of the dispersion relations and polarizations of adsorbate modes and surface phonons is presented. The dispersion of the Rayleigh phonon is in good agreement with the experimental EELS data. The changes in interatomic force constants are discussed.

Vibrational states on Pd surfaces

We present the calculation of vibrational modes and lattice relaxation for the Pd(100), (110) and (111) surfaces. The surface phonon frequencies and polarizations are obtained using embedded-atom potentials. Comparison of the calculated frequency values with available experimental data gives agreement within 0.2 THz.

Vibrational states on lithium and sodium surfaces

We present the calculation of vibrational modes, surface energy and lattice relaxation for the (100) and (110) surfaces of lithium and sodium. These values are calculated with the use of interatomic potentials generated within the embedded atom method (EAM). It was found that EAM potentials give an expansion of a few first interlayer spacings. Calculated values of surface energy are in good agreement with available theoretical and experimental data. It is shown that the dependence of the surface energy on the lattice relaxation is extremely small. True and resonance surface states are observed on all surfaces of interest along the symmetry directions and at the symmetry points of the two-dimensional Brillouin zone. It is found that in the case of a (110) surface the phonon frequencies have only a slight dependence on the lattice relaxation. Some more influence is observed for the (100) surface.

Phonon states on the (100), (110) and (111) aluminium surfaces

We present the calculation of vibrational states on the relaxed surfaces (100), (110) and (111) of aluminium. The surface phonon frequencies and polarizations are calculated with the use of the interatomic interaction potential obtained in the framework of the embedded-atom method. New surface modes have been found on the Al(100) surface along the \gGM direction and at the X and M symmetry points. On the Al(110) surface new surface phonon states have been obtained along the \gGX, \gGȲ directions and at the \gG and Ȳ points. For the Al(111) surface the present calculation gives new surface modes along \gGK and \gGM. Two surface modes are observed within the energy gap at the K point.

Self-consistent calculation of the electron energy spectrum of aluminum

The local density function approximation is used to construct a fundamental nonlocally soft pseudopotential for aluminum which satisfies the norm conservation condition. This pseudopotential is used to perform a self-consistent calculation of the aluminum electron energy spectrum, which proves to agree well with experimental data. The effect of various pseudopotentials (constructed with norm conservation) on the form of the energy spectrum is studied. It is shown that these various pseudopotentials lead to identical results.

Contribution of phonons to the line width of surface electronic states on Pd(111)

This paper reports on the results of calculations of the contributions from the electron-phonon interaction to the line width of the surface electronic states on Pd(111). The calculations have been performed both using an ab initio method based on the electron density functional theory and the linear response method in the pseudopotential representation with a mixed basis set and using a model that includes the description of the electronic structure of the surface by a one-dimensional model potential. The phonon contribution to the width of the lines has been analyzed for all the surface states under consideration. It has been demonstrated that the line width due to the electron-phonon interaction exhibits a weak anisotropy and that the character of changes in the line width with variations in the energy and the wave vector of the electron depends first of all on the particular surface energy band.

Diffusional and Vibrational Properties of Cu(001)–c(2 × 2)–Pd Surface Alloys

Interatomic interaction potentials constructed in the framework of the embedded-atom method are used to study the structural, diffusional, and vibrational properties of ordered Cu(001)-c(2×2)-Pd surface and subsurface alloys. The equilibrium structures obtained for these alloys are in good agreement with experimental data and the results of other calculations. The calculated diffusional characteristics are consistent with the experimental kinetics and evolution of the surface alloys and attest to the stability of the subsurface alloy. The activation energy for planar diffusion of palladium in the initial stage of the alloy formation agrees with the value measured using scanning tunneling microscopy. The calculated surface phonon frequencies agree well with the experimental values obtained using electron-energy-loss spectroscopy. The results show that the Cu-Pd bond is strong and that the bond between surface copper atoms weakens.

Vibrational states of the Cu(100) surfaces with nickel adlayers

The vibrational spectra of the Cu(100) surface covered with one or two Ni monolayers are calculated using the embedded-atom method. The surface relaxation, the dispersion of surface phonons, and the polarization of vibrational modes of the adsorbate and the substrate are discussed in detail. The theoretical results are in good agreement with experimental data and can be used for their interpretation. The changes observed in the interatomic interactions upon application of nickel adsorbates to the copper substrate are considered.