Vibrational modes on the Al\,(111) - (\sqrt 3 \times \sqrt 3 )R30^\circ - Na surface

The vibrational spectra on the $Al\,(111) - (\sqrt 3 \times \sqrt 3 )R30^\circ - Na$ surface are calculated by the embedded atom method. Surface relaxation, dispersion of surface phonons, local density of surface states, and polarization of vibrational modes of adatoms and substrate atoms are discussed in the present paper. The theoretical results obtained agree well with the available experimental data and can be used for their interpretation.     

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.     

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.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 56–62, September, 1984.     

Lattice Dynamics of Bi2Те3 and Vibrational Modes in Raman Scattering of Topological Insulators MnBi2Te4·n(Bi2Te3)

JETP Letters - This work is devoted to the experimental study and symmetry analysis of the Raman-active vibration modes in MnBi2Te4·n(Bi2Te3) van der Waals topological insulators, where n is...     

Mode-selected electron-phonon coupling in superconducting Pb nanofilms determined from He atom scattering

The electron-phonon coupling (EPC) strength for each phonon mode in superconducting Pb films is measured by inelastic helium atom scattering (IHAS). This surprising ability of IHAS relies on two facts: (a) In ultrathin metal films, the EPC range exceeds the film thickness, thus enabling IHAS to detect most film phonons, even 1 nm below the surface; (b) IHAS scattering amplitudes from single phonons are shown, by first-principle arguments, to be proportional to the respective EPC strengths. Thus IHAS is the first experiment providing mode-selected EPC strengths (mode-lambda spectroscopy).     

Diffusional and vibrational properties of Cu(001)-<Emphasis Type="Italic">c</Emphasis>(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.     

Electronic structure and excitations on clean and nanostructured metal surfaces

We present a brief overview of recent studies and new theoretical results for electron-phonon interaction in the $\overline{Y}$ surface states on FCC(110) noble metal surfaces as well as in surface and quantum-well states of thin films. We discuss the oscillations of electron-phonon coupling parameter λ and the respective contribution to the lifetime broadening of these states. We analyse the effect of spin-orbit splitting of surface states on an electron-electron contribution to lifetimes of excited electrons (holes). Oscillations of the electron-electron contribution and quadratic dependence of the linewidth on energy is discussed for ultrathin Pb(111) films.     

Electron-phonon interaction in a free standing beryllium monolayer

We report ab initio study of the electron-phonon coupling in a free standing Beryllium monolayer. The calculations were carried out using a linear-response approach in the plane-wave pseudopotential representation. The Eliashberg spectral function α²F(ω) and the electron-phonon coupling parameter λ are evaluated at the Fermi level. The obtained results show a large contribution to the electron-phonon coupling from the low-energy transverse mode scattering.     

Surface phonons on Pb(111)

We present an ab initio study of the lattice dynamics of the Pb(111) surface. The calculations were carried out within the density-functional theory using a linear response approach in the mixed-basis pseudopotential representation. We observe a rich spectrum of surface localized modes, and make a detailed assignment to measured modes in a recent helium-atom scattering experiment. We find that the inclusion of spin–orbit coupling considerably softens the phonon spectrum of the surface, thereby improving the agreement with experiment significantly.     

The effect of spin-orbit coupling on the surface dynamical properties and electron-phonon interaction of Tl(0001)

We present an ab initio study of the effect of spin-orbit coupling on the dynamical properties of the Tl(0001) surface as well as on the electron-phonon interaction at the surface. The calculations based on density-functional theory were carried out using a linear response approach and a mixed-basis pseudopotential method. It is shown that the spin-orbit effects on the phonon spectrum and the electron-phonon interaction at the Fermi level of the surface are weak but conspire to a reduction in the electron-phonon coupling strength by 16%.