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The interplay of the atomic structure and phonon spectra in a variety of two dimensional phases forming during submonolayer Pb adsorption on a Cu(001) surface has been investigated using embedded atom method interatomic interaction potentials. Complementary calculations of the equilibrium atomic structure of these phases were performed using density functional theory. It has been shown that the dynamic stability of the Pb/Cu(001) structures increases with increasing the coverage from 0.375 ML to ultimately 0.6 ML, when a dense Pb layer is formed. The increase of the coverage also results in progressive shift of the Rayleigh mode of the copper surface to higher energy and the appearance of new mixed adsorbate–substrate vibration modes., This work was supported by the government research assignment for ISPMS SB RAS (project FWRW-2022-0001). more...

The local structural changes and vibrational characteristics of the (001) surface of an fcc metal in the presence of vacancy/adatom point defects have been studied theoretically. The effect of the size of the vacancy defect and the position of the adatom in it on the character of structural relaxation and on the phonon states of the surface has been demonstrated. The most dynamically stable configuration in the complex of vacancy/adatom point defects has been determined. Data on the equilibrium atomic configuration, local density of phonon states, and polarization of localized vibrational modes have been analyzed. All calculations have been performed with interatomic potentials constructed with the embedded atom method. more...

The structural and vibration properties of the (√3 × √3)R30°–Cr adsorption structure on the Cu(111) surface and the Cu(111)–(√3 × √3)R30°–Cr two-dimensional alloy incorporated into the S – 1 substrate layer are studied using the tight binding approximation. Surface relaxation is discussed along with the dispersion of surface phonons and the local density of vibration states of adatoms and substrate atoms. It has been demonstrated that the presence of chromium atoms modifies the structural and vibration characteristics of the substrate and leads to the appearance of new phonon states in it. The analysis of the entire set of data has shown that the Cu(111)–(√3 × √3)R30°–Cr subsurface two-dimensional alloy is a more stable configuration. more...

Using the potentials, generated by a tight binding approximation, the equilibrium atomic structure and the phonon spectra of Cr and Ni thin films (one monolayer) deposited on the Cu (111) surface are calculated. The atomic relaxation, the vibrational state density distribution on the Cr, Ni and substrate atoms and the polarization of vibrational modes are considered. The change in the phonon spectrum during film deposition and the segregation of Cu atoms on the film surface are discussed. It is shown that mixing of the Cr and Ni atomic vibrations with those of the substrate takes place in the entire frequency range, resulting in a frequency shift of the vibrational modes of the substrate and the formation of new vibrational states not typical for a clean surface. The Cu/Cr/Cu and Cu/Ni/Cu structures are found to be more stable dynamically. more...

Mechanisms of atomic layer-by-layer formation of the equilibrium structure of multilayer Na film on the Cu(001) surface have been studied taking into account relaxation and dynamic (phonon) processes. It has been shown that the atomic rearrangement of the substrate-commensurate с(2 × 2) superstructure of the first Na monolayer to a bcc (110)-oriented structure begins with the second monolayer. The dynamic contribution to the formation of the structure of the growing Na film has been estimated. It has been shown that phonon modes select exponentially observed structures from statically favorable structures. All calculations have been performed with interatomic potentials constructed with the embedded atom method. The comparison of the calculated vibrational frequencies with the existing experimental data has demonstrated their good agreement., This work was supported by the Siberian Branch, Russian Academy of Sciences (project no. III.23.2.9, basic research program for 2019–2021). The numerical calculations were supported by the Mendeleev Foundation, Tomsk State University (project no. 8.1.01.2018). We are grateful to Prof. G. Benedek for stimulating discussion. more...

This article is part of the themed collection: Festschrift for Peter Toennies - New Horizons in the Dynamics of Molecules: from Gases to Surfaces., The structure and magnetic properties of small Cr clusters, Cr3 and Cr4, adsorbed on the Cu(111) surface have been investigated using density functional theory (DFT) calculations and their vibrational properties have been studied within calculations based on tight-binding second moment approximation interatomic interaction potentials (TBSMA). It has been shown that the magnetic ordering in the Cr clusters significantly affects their crystal structure and symmetry, which influences the vibrational modes of the clusters and nearest neighbor copper atoms. In turn, these modes select potentially possible structures of Cr3 and Cr4, prohibiting the lowest total energy cluster structure as dynamically unstable., This work was supported by the Government Research assignment for ISPMS SB RAS, Project No. III.23.2.9. E. V. C. acknowledges partial support from Saint Petersburg State University (Grant No. ID 51126254). more...

The paper presents the results of theoretical investigations of the equilibrium atomic configurations and electronic properties of dimers and trimers of p-elements of IV (Pb), V (Bi) and VI (Te) groups as well as their cations and anions. The density functional theory calculations are used to obtain the equilibrium bond lengths and binding energies, vibrational frequencies, the HOMO-LUMO gaps for heavy element clusters with a strong relativistic effect. It is shown that spin-orbit coupling should be taken into consideration due to its substantial effect on energy and oscillating parameters of clusters. more...

The submonolayer adsorption of Na onto the Cu(110) surface is studied. At small Na coverages (Θ = 0.16–0.25 ML), the substrate surface subjected to missing-row reconstruction (1 × 2) is shown to be most stable dynamically. When the coverage increases to Θ = 0.5 ML, the unreconstructed substrate surface with a c(2 × 2) sodium adlayer becomes dynamically stable. For an analysis, we used data on the equilibrium atomic configuration, the adsorption energy, the phonon spectra, the local density of phonon states, and the polarization of localized vibrational modes. All calculations were performed using the interatomic potentials obtained in terms of the embedded-atom method. The calculated frequencies of localized vibrational modes agree well with the existing experimental data. more...

Using first-principles total-energy calculations, lattice relaxation have been determined for Al (001), Sn (001) and Sn (010) surfaces, as well as of the adsorbed system Sn/Al (001). Results for clean surfaces as well as for Al (001) surface covered by submonolayer of Sn will be presented and compared with available experimental information. more...

The magnetic properties of single- and multicomponent trimers of heavy p-elements of Groups IV-VI (Pb, Bi, Te) with a pronounced relativistic effect, as well as their anions and cations, are studied. Spin and orbital magnetic moments of the considered clusters are calculated using the formalism of the density functional theory. For most clusters, calculations reveal nonzero magnetic moments. It is shown that the spin-orbit coupling significantly affects the spin magnetic moment in such clusters. The energy of magnetic anisotropy is calculated for all neutral and charged trimers and the direction of the easy magnetization axis is determined. more...

Equilibrium lengths and binding energies, vibrational frequencies, width of the HOMO–LUMO gap, and the magnetic anisotropy energies for one- and two-component dimers of heavy p elements of Groups IV (Sn, Pb), V (Sb, Bi), and VI (Se, Te) with a pronounced relativistic effect have been calculated with the use of the formalism of the density functional theory. It has been shown that it is necessary to take into account the spin–orbit coupling, which significantly affects the energy parameters of clusters. The analysis of the data obtained has revealed that the Pb–Te, Pb–Se, Sn–Te, and Sn–Se dimers have the widest gap at the Fermi level and the lowest reactivity. The magnetic anisotropy energy has been calculated for all single- and doublecomponent dimers and the direction of the easy magnetization axis has been determined., This work was performed within the Program of Basic Scientific Research for State Academies of Sciences for 2013–2020 and was supported by the Russian Foundation for Basic Research (project no. 15-02-02717-a). more...

We present a theoretical investigation of the structural and vibrational properties of ordered 2D phases formed by the Li, Na and K atoms on the Cu(0 01) surface. The lattice relaxation, phonon dispersions and polarization of vibrational modes as well as the local density of states are calculated using the embedded-atom method. The obtained structural parameters and vibrational frequencies are in close agreement with available experimental results., This work was performed within the frame of the Fundamental Research Program of the State Academies of Sciences for 2013–2020, line of research III.23. We also acknowledge the support from the Academic D I Mendeleev Fund Program of Tomsk State University (Project No. 8.1.01.2018). more...

The equilibrium atomic structure and the phonon spectra of a submonolayer (θ = 0.5 monolayer) Ni film deposited on the surface of Cu(100) are calculated using the potentials obtained by the embedded atom method. We consider atomic relaxation, the vibrational state density distribution on Ni and substrate atoms, and polarization of vibrational modes. Variation of the phonon spectrum upon segregation of Cu atoms on the film surface is considered. It is shown that mixing of vibrations of Ni adatoms with vibrations of substrate atoms occurs in the entire frequency range, leading to a frequency shift of the vibrational modes of the substrate and to the occurrence of new vibrational states atypical of a clean surface. The Cu(100)–c(2 × 2)–Ni structure is dynamically stabler when placed in the subsurface layer of the substrate. more...

The atomic and phonon structures of a Pb ultrathin film on the Al(100) surface have been theoretically studied. Surface relaxation, local density of vibrational states, and polarization of the phonon modes of adatoms and atoms of a substrate have been discussed. It has been shown that the adsorption of Pb results in the oscillating relaxation of the surface of the substrate and warping of the structure in subsurface layers. Comparative analysis of the vibrational characteristics of the pure surface of the substrate and the surface with adatoms has shown that the adsorptive interaction in the system and its dynamic stability are governed by new vibrational modes that are not inherent in pure Al and Pb surfaces., This work was supported by the Government of the Russian Federation (Program of Basic Research at State Academies of Sciences for 2013–2020). The numerical calculations were performed at the SKIF Cyberia supercomputer (Tomsk University). more...

The equilibrium bond lengths and binding energy, second differences in energy and vibrational frequencies of free clusters Nin (2 ≤ n ≤ 20) were calculated with the use of the interaction potential obtained in the tight-binding approximation (TBA). The results show that the minimum vibration frequency plays a significant role in the evaluation of the dynamic stability of the clusters. A nonmonotonic dependence of the minimum vibration frequency of clusters on their size and the extreme values for the number of atoms in a cluster n = 4, 6, 13, and 19 are demonstrated. This result agrees with the theoretical and experimental data on stable structures of small metallic clusters. more...

We present a theoretical investigation of the structural and vibrational properties of the K/Cu(110) adsorbed systems using the embedded atom method. The surface relaxation, phonon dispersions, and polarization of vibrational modes as well as the local density of states have been calculated as a function of potassium coverage on reconstructed and unreconstructed Cu(110) surface. On the reconstructed surface, two K-substrate stretching modes have been found, which do not show any coverage dependence. The obtained vibrational frequencies of surface states are in close agreement with available experimental data., This work was carried out via the financial support of a grant (8.1.05.2015) from The Tomsk State University Academic D. I. Mendeleev Fund Program, Saint Petersburg State University (Grant no. 15.61.202.2015), RFBR grant (15-02-02717-a), Fundamental Research Program of the State Academies of Sciences for 2013−2020. more...

Vibrational spectrum of the ordered Pt(111)– $$ \left( {\sqrt {3} \times \sqrt {3} } \right) $$ R30°–K surface superstructure formed on the platinum surface with adsorption of 1/3 ML potassium is calculated with the use of the interatomic interaction potentials obtained in the strong bond approximation. Relaxation of the surface, dispersion of the surface phonons, local density of vibrational states, and polarization of phonon modes of adatoms and atoms of the substrate are discussed in the work. The theoretical results obtained agree well with the available experimental data. more...

6 páginas, 3 figuras, 1 tabla., The binding energies and vibration frequencies of free small cobalt clusters containing up to twenty atoms inclusive have been calculated using the interatomic interaction potential obtained in the tight-binding approximation. The minimum frequency of the cluster vibrations has been shown to play the determining role in the evaluation of its dynamic stability. The analysis of the energy parameters and vibrations of clusters has demonstrated that the cobalt clusters in which the number of atoms is n = 4, 6, 13, and 19 are stable. more...

5 páginas., The relaxation and vibrational properties of both Al clusters and the (111) surface of a copper sub-strate were studied using the interatomic interaction potentials obtained in a tight-binding approximation. The presence of small aluminum clusters led to modification of the vibrational states of the substrate, a shift of the Rayleigh mode, and excitation of new Z-polarized modes. Hybridized modes localized on the cluster adatoms and the neighboring atoms of the substrate were found in the phonon spectrum. The localized dipole-active modes of the cluster and their strong hybridization with vibrations of the substrate points to desorption stability of the tri- and heptaatomic clusters. more...

The vibrational spectra of the Pt(111)-p(2 × 2)-K ordered surface superstructure formed on the platinum surface upon adsorption of 0.25 potassium monolayer are calculated using the interatomic interaction potentials obtained within the tight-binding approximation. The surface relaxation, the dispersion of surface phonons, the local density of surface vibrational states, and the polarization of vibrational modes of adatoms and substrate atoms are discussed. The theoretical results are in good agreement with the recently obtained experimental data. more...

The electron-phonon interaction in the quantum well state formed by a Na monolayer coating on Cu(111) is investigated theoretically. The calculations show that the electron-phonon coupling constant γ in this state decreases insignificantly (≈1%) compared to the value of γ for a clean copper surface. The corresponding electron-phonon contribution to the lifetime τ of the quantum well state increases by a factor of 1.5 compared to τ for the clean Cu(111) surface. more...

The growth of Pb ultrathin films on Cu(111) has been long studied in connection with electronic quantum-size effects and for the different temperature-dependent growth kinetics. At low temperature the formation of a wetting layer (1 monolayer (ML)), is followed by an instability of the 2 ML film and a regular layer-by-layer growth is then only observed for more than two monolayers. The 2 ML film was, however, shown to be stabilized by alloying Pb with 20% Tl. This work presents a theoretical study of the dynamics of the wetting layer as well as for 2 ML Pb0.8Tl0.2, 3 and 4 ML Pb on Cu(111) in the 4 × 4 commensurate phase, for which detailed inelastic Helium atom scattering (HAS) spectra have been measured. The present calculations based on the embedded atom method (EAM) include the dynamics of the substrate. Besides leading to a detailed interpretation of the HAS experimental data, the present results are compared with a previous density-functional perturbation theory (DFPT) study for 3 to 7 ML Pb on a rigid substrate. The comparison reveals the role played by the substrate dynamics at the smallest thicknesses, despite the large mass and stiffness differences between Pb and Cu. Also the different thermal expansion of the film with respect to the substrate is shown to cause appreciable anomalies in the temperature and thickness dependence of the phonon dispersion curves., The work was carried out at the financial support by a grant (8.1.05.2015) from The Tomsk State University Academic D. I. Mendeleev Fund Program, an RFBR grant (15-02-02717-a), and the Fundamental Research Program of the State Academies of Sciences for 2013–2020. more...

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. more...

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. more...

Vibrational properties of the small tetrahedral cluster of Co on the Cu (111) surface are studied by using tight-binding second moment approximation interatomic interaction potentials. It was shown that interaction of the clusters with substrate leads to arising of frustrated translation and frustrated rotation in-plane polarized vibrational modes localized on the cluster atoms. The Co4 cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations. more...

The binding energy, equilibrium geometry, and vibration frequencies in bimetallic clusters Ni13 − n Al n (n = 0–13) have been calculated using the embedded atom method potentials. It has been shown that the icosahedral structure is the most stable in monoatomic and bimetallic clusters. A tendency of Al atoms to segregate on the cluster surface has been revealed in agreement with the experimental data. The calculations of the atomic vibrations have shown the nonmonotonic dependence of the minimum and maximum vibration frequencies of cluster atoms on its composition and the coupling of their extreme values with the most stable atomic configuration. The increase in the number of Al atoms leads to the shift of the frequency spectrum and the substantial redistribution of the localization of vibrations on the cluster atoms., This work was supported by the Russian Foundation for Basic Research (project no. 15-02-0271-7a) and the St. Petersburg State University (project no. 11.50.202.2015). more...

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. more...

Collective vibrational modes of crystal lattices, called phonons, determine fundamental material properties, such as their thermal and electrical conductivities. Bulk phonon spectra are influenced by point defects. More recently, the importance of phonons on nanostructures has come into the focus of attention. Here we show a spatially resolved phonon spectra of point defects that reveal distinctly different signatures for a cavity alone and an impurity atom fully integrated into the surface as opposed to one placed into a cavity. The spectra are indicative for delocalized phonons and localized vibrations, respectively, as confirmed by theory. more...

We investigated the structural and vibrational properties of the Cu (100) surface covered with ultrathin (1-5 ML) Ni films using interaction potential from the embedded atom method. The surface relaxation, dispersion relation and polarization of vibrational modes are discussed. Our calculated structural parameters are in good agreement with experimental results. The obtained vibrational frequencies compare well with the available experimental data. more...

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. more...

The binding energy, equilibrium geometry, and vibration frequencies of free clusters Cu n (2 ≤ n ≤ 20) are calculated using the potentials of interatomic interactions found using the tight-binding approximation. The nonmonotonic dependence of the clusters' minimum vibration frequency on their sizes and the extreme values for the number of atoms in a cluster n = 4, 6, 13, and 19 is demonstrated. It is noted that this result agrees with the theoretical and experimental data on stable structures of small and medium metallic clusters. © 2013 Pleiades Publishing, Ltd. more...

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. more...

The vibrational properties of the Al(001)-c(2 × 2)–Na (Li) ordered phases formed by alkali atoms (Na and Li) on the Al(001) surface at low and room temperatures are presented. The equilibrium structural characteristics, phonon dispersions and polarization of vibrational modes as well as the local density of phonon states are calculated using the embedded-atom method. The obtained structural parameters are in close agreement with experimental data. more...

Vibrational properties of tetrahedral clusters of Cu and Co on the Cu(111) surface are studied by using interatomic interaction potentials constructed within tight-binding second moment approximation. It was shown that interaction of the Co4 and Cu4 clusters with the substrate leads to arising of frustrated translation and frustrated rotation in-plane polarized vibrational modes localized on the cluster atoms. The vibrational modes of the free Cu4 cluster upon its adsorption on the Cu(111) surface mix with Cu bulk phonons and become almost delocalized. Contrary to that, in the Co4 cluster on the surface the high frequency modes remain strongly localized and mixed with the nearest neighbor atoms vibrations. The highest frequency vibration of the Co4 cluster splits due to different interaction with certain groups of nearest neighbor atoms., The work has been supported by SB RAS (Project 3.6.1.1.). more...

4 páginas, 2 figuras.-- PACS number(s): 68.37.Ef, 63.20.Pw, 68.35.Ja, The vibrational spectrum of a tunneling junction on a clean Cu(111) surface has been characterized by vibrational density of states calculations and inelastic electron tunneling spectroscopy technique. We demonstrate that the achieved spectrum consists not only of vibrational modes excited by the tunneling electrons on the clean surface but also of modes characteristic of the structure of the tip apex. This allows to identify unequivocally the atomic structure of the tip, which is still the largest unknown parameter in a scanning tunneling microscope. This opens a new perspective in the interpretation of the measurements of vibrational modes with a scanning tunneling microscope. Additionally, it might have implications in the measurements of electron conductance through single atom or molecules contacted by the tip of scanning tunneling microscope. more...

Vibrational properties of small cobalt clusters (dimer and trimer) adsorbed on the Cu(111) surface are studied using interatomic interaction potentials obtained in a tight-binding approximation. The complete (lateral and vertical) relaxation of the surface, the local phonon density of states, and the polarization of vibration modes of clusters and atoms of the substrate are discussed. It is shown that the adsorption of small cobalt clusters leads to a local modification of the vibrational properties of the substrate surface and to excitation of new vibration modes localized on both the cluster adatoms and substrate surface atoms. An increase in the cluster size causes a decrease in the intensity of peaks of the local density of states and their broadening and also a shift in the frequencies of the peaks. more...

Vibrational properties (frequencies, polarizations, and lifetimes) of a single adatom, dimer, and trimer of Co on low-index Cu surfaces, Cu(111), Cu(001), and Cu(110) are studied by using tight-binding second moment approximation interatomic interaction potentials. We show that structural and vibrational properties of the Co clusters strongly depend on the substrate orientation. The longest lifetimes of 1–2.5 ps have been found for high-frequency z-polarized vibrations in all the Co clusters considered. The shortest lifetimes of 0.1–0.8 ps have been obtained for low-frequency horizontal (frustrated translation) vibrational modes., This work was partially supported by the University of the Basque Country Grant No. 9/UPV 00206.215-13639/2001 and the Spanish Ministerio de Ciencia y Tecnología Grant No. FIS 2004-06490-C03-01. more...

Structural and diffusion properties of a Cu(0 0 1)-c(2 × 2)–Pd surface and sub-surface ordered alloys are studied by using interaction potentials obtained from the embedded-atom method. The calculated diffusion energies are in agreement with observed kinetics of the surface alloy formation and confirm stability of the underlayer alloy. Activation energy of planar diffusion of palladium at the initial stage of the alloy formation as well as the activation energy of the overlayer–underlayer diffusion of the Pd atoms are in good agreement with those obtained by the scanning tunneling microscopy and low energy electron diffraction measurements, respectively., This work was partially supported by the Siberian Branch of RAS (Integration Project 216) and by the Basque Country Government. more...

We present calculation results for electron–phonon (e–ph) coupling in one monolayer (ML) of Na on the Cu(1 1 1) surface. We show that the e–p coupling parameter λ decreases compared to that for clean Cu(1 1 1) due to the significant decrease of the Na vertical vibrational mode contribution to the Eliashberg function in the 1 ML Na/Cu(1 1 1) system. The corresponding phonon induced lifetime broadening Γe–ph of a quantum-well state at low temperature decreases by 30% compared to that on clean Cu(1 1 1)., Partial support by the Basque Departamento de Educación, Universidades e Investigación, the University of the Basque Country UPV/EHU (Grant No. 9/UPV 00206.215-13639/2001), the Spanish MEC (Grant No. FIS2004-06490-C03-00), the Ministry of Science of Russia (Grant No. 40.012.1.1.1153) and NATO science programme (Grant PST. CLG. 980395) is acknowledged. more...

We present the results of a comparative study of the equilibrium crystal structure and vibrational properties of the Na∕Cu(111) system at coverages up to monolayer saturation. The calculations are performed with interaction potentials from the embedded-atom method. The following ordered structures are considered: p(3×3), p(2×2), (√3×√3)30°, nd (3∕2×3∕2). The surface relaxation, phonon dispersion, and polarization of vibrational modes for the adsorbate and substrate atoms as well as the local density of states are discussed. It is found that the bond length between an adsorbate and the nearest-neighbor substrate atom slightly increases with increasing coverage. Adsorption of sodium also results in a small rumpling in two upper substrate layers. The mode associated with adatom-substrate stretch vibrations was obtained in our calculation at about 22meV for all the structures considered. The strength of this mode decreases with increasing coverage in accordance with the experiment. On the other hand, we find that the frustrated translation mode frequency of sodium on Cu(111) is strongly coverage dependent., This work was supported by the Ministry of Science of Russia Grant No. 02.434.11.2027 and NATO science program Grant No. PST.CLG.980395. more...

In this paper we present the results of a comparative study of vibrational and structural properties of the ordered (√3x√3) R30º and c(2 × 2) phases formed by Na adatoms at room temperature on the Al(1 1 1) and Al(1 0 0) surfaces, respectively. The surface relaxation, surface phonon dispersion, and polarization of vibrational modes are calculated using the embedded-atom method. Our calculated structural parameters are in agreement with experimental and ab initio results. The obtained vibrational frequencies compare fairly well with available experimental data., This work was supported by Russian Government grant (02.434.11.2027) and NATO-project grant (PST. CLG. 980395). more...

We investigated the vibrational and structural properties of the Al(111)−(√3×√3)R30°−AM (AM=Na,K,Li) adsorbed systems using interaction potentials from the embedded-atom method. The surface relaxation, surface phonon dispersion, and polarization of vibrational modes for the alkali adatoms and the substrate atoms as well as the local density of states are discussed. Our calculated structural parameters are in close agreement with experimental and ab initio results. The obtained vibrational frequencies compare fairly well with the available experimental data., This work was partially supported by the Ministry of Science of Russian Federations Grant No. 40.012.1.1.1153 d, NATO science programmes Grant PST. CLG. 980395d, and the Basque Country Government. more...

Using interaction potentials from the embedded-atom method we investigated the structural and vibrational properties of a Cu(100)-c(2 × 2)-Pd surface alloy and an underlayer c(2 × 2) alloy with a mixed CuPd second layer. The calculated surface phonon frequencies are in agreement with the experimental values obtained by electron energy-loss spectroscopy. From the calculated local phonon densities of states we find that surface effects are most pronounced in the first two layers for both systems studied. The results also indicate a very strong Pd-Cu bonding accompanied by a weaker bonding of the Cu surface atoms to their nearest neighbors. This has considerable influence on the surface phonon frequencies. more...

Vibrational modes, surface energy, and surface relaxation on the (001) surface (hexagonal plane type $C)$ of $9R$ Li are calculated using the embedded-atom method. A detailed discussion of the local phonon densities of states, the changes in interatomic force constants, and a comparison with the results for the hexagonal surface (110) of bcc Li are presented. For both surfaces considered the surface effect on the phonon densities is found to be significant only in the first three layers. The results show that interactions between atomic layers are weaker in the surface region compared to bulk values. This effect together with a substantial softening in the phonon spectrum for the (110) surface of bcc Li may favor the nucleation of the martensitic phase along preferable directions at the surface. more...

We present results of a comparative study of the vibrational spectrum and local density of phonon states in ordered p(2 × 2) and (√3 × √3)R30° structures formed by potassium atoms on the Pt(111) surface. The calculations were performed with tight-binding interatomic interaction potentials. It was found that the mode associated with vertical displacements of K adatoms has an energy of about 20 meV in both K structures. The strength and energy of this mode slightly decreases with increasing coverage. This result is in good agreement with available experimental data. As in time-resolved second harmonic generation measurements, we observed low frequency modes for both structures considered, which are caused by the interaction of potassium with the second layer of the substrate. © 2012 IOP Publishing Ltd., We acknowledge financial support by the RFBR (Proj. N 11-08-00460-a). more...

10 pages., We review the current progress in the understanding of vibrations of alkalis adsorbed on metal surfaces. The analysis of alkali vibrations was made on the basis of available theoretical and experimental results. We also include in this discussion our recent calculations of vibrations in K/Pt(111) and Li(Na)/Cu(001) systems. The dependence of alkali adlayer localized modes on atomic mass, adsorption position and coverage as well as the dependence of vertical vibration frequency on the substrate orientation is discussed. The square root of atomic mass dependence of the vertical vibration energy has been confirmed by using computational data for alkalis on the Al(111) and Cu(001) substrates. We have confirmed that in a wide range of submonolayer coverages the stretch mode energy remains nearly constant while the energy of in-plane polarized modes increases with the increase of alkali coverage. It was shown that the spectrum of both stretch and in-plane vibrations can be very sensitive to the adsorption position of alkali atoms and substrate orientation., The work was partially supported by the Basque Country University and the Siberian Branch of RAS (grant No. 206). GB is grateful to the Donostia International Physics Center for supporting his visit to DIPC. more...

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. more...