A one parameter model potential for noble metals

A phenomenological one parameter model potential which includes s-d hybridization and core-core exchange contributions is proposed for noble metals. A number of interesting properties like liquid metal resistivities, band gaps, thermoeletric powers and ion-ion interaction potentials are calculated for Cu, Ag and Au. The results obtained are in better agreement with experiment than the ones predicted by the other model potentials in the literature.     

Calculations of vacancy formation energies and divacancy binding energies for noble metals using pseudopotential formalism

Vacancy formation energies (E^f_1v) and divacancy binding energies (E^B_2v) for noble metals have been calculated using the Moriarty's pseudopotential. While the calculated E^f_1v are coincident with the experimental values except Cu, E^B_2v agree with them for all the metals tolerably.     

A model pseudopotential and energy wave number characteristics of simple metals

A model pseudopotential for electron-ion interaction in simple metals is proposed. The screened form factors of the potential are presented for 25 simple metals. Using this model potential, the energy wave number characteristics for these metals are determined. For sodium, potassium and lead, the results are compared with the numbers obtained from the analysis of experimental phonon frequencies and other theoretical calculations.     

The effect of van der Waals-type interactions in metals: A pseudopotential model

A model has been developed for the long-range part of the ion-ion interaction of simple metallic many-particle systems. The investigation is based on the local pseudopotential theory. The essential point in the examination is the consideration of interactions of van der Waals-type in the determination of the direct ion-ion potential and the ion-electron pseudopotential. Numerical calculations performed for liquid rubidium near the melting point show that these interactions are distinctly reflected in the long-range part of the ion-ion potential. The reference potential used in the study had been calculated without parameters by means of the experimentally determined pair correlation function.     

A pseudopotential based theory of the driving forces for electromigration in metals

We present a pseudopotential calculation of the driving forces for atomic migration in metals in the presence of electron currents. When electrons are scattered by impurities in a metal, we find that a force is generally exerted on each atom in the vicinity of the scattering center. Because the scattering is predominantly elastic, it is possible to express this force field as the classical electrostatic force arising from the total electronic charge, as has been assumed by Friedel and Bosvieux. The electron charge density is determined from a pseudopotential calculation, and the resulting force is expressed as a sum of effective interactions between the diffusing atom and all crystal defects.The forces on an atom arising from the electron scattering and from the applied electric field together comprise the driving force which causes a net current of atoms. The driving forces are calculated for intestitial and vacancy migration in several metals, and the results are found to compare favorably with most experimental data.     

A power-law model of the pseudopotential

A new simple power-law model of the pseudopotential is suggested. The parameters of the pseudopotential are determined for ions of the second period of the periodic system. Excited energy levels calculated for these ions using this model demonstrate its convergence. The accuracy of the energy levels calculated for the excited states is <10⁻³ a.u.     

Lattice dynamics of FCC transition metals: A pseudopotential approach

Simple pseudopotential model for the binding energy of transition metals is proposed. The contribution of thes-like electrons is calculated in the second-order perturbation theory for the local model pseudopotential while that of thed-like electrons is taken into account by introduction of repulsive short-range interatomic potential. Model parameters were determined for ten fcc transitions metals (Cu, Ni, Fe, Co, Ag, Pd, Rh, Au, Pt, and Ir). This model was used for the calculation of the phonon dispersion and the density of states, as well as for the elastic constants and their pressure derivatives. Good agreement with experimental data was achieved for the overall shape of phonon spectra and even for the position of the Kohn anomalies in Pd and Pt. Existence of such anomalies is also stated for predicted phonon spectra of rhodium and iridium.     

General model pseudopotential for positive ions

A phenomenological general model pseudopotential of the positive ions is presented in a closed analytic form without free parameters.     

A general pseudopotential model for molecules with many valence electrons

Criteria are discussed for the practical application of ‘valence-electron only’ calculations aimed at simulating ab initio all-electron calculations on molecules containing heavy atoms with many core electrons. A theoretical model is outlined based on the use of pseudopotentials derived from atomic SCF calculations. The model has been used in calculations for NaH, Na₂, H₂S, S₂, H₂S₂, HCl, Cl₂ and NaCl, and has been tested by comparison with reference all-electron calculations. Most of these tests employ double-zeta basis sets and SCF wavefunctions, although polarization functions and complete valence-electron CI wavefunctions have been used in some cases. The model is generally successful for ground-state equilibrium structures, charge distributions and orbital energies.     

Solubility of noble metals in hcp metals: A test for the validity of pseudo-potentials

In the calculation of the energy-band structureU _BS dependence of hcp metal-noble metal dilute alloys on the axialc/a and electron per atome/a ratios, we have used two different types of the pseudo-potential for the noble metals in the virtual crystal approximation. By comparing the experimental data on noble metal-simple hcp metal solubility limits with theoretical curves forU _BS, we show how this type of calculation can serve as one of the criteria for determining the solubility limits and the validity of a given pseudo-potential in the dilute alloy limit.     

Hole dynamics in noble metals

Hole dynamics in noble metals (Cu and Au) is investigated by means of first-principles many-body calculations. While holes in a free-electron gas are known to live shorter than electrons with the same excitation energy, our results indicate that d holes in noble metals exhibit longer inelastic lifetimes than excited sp electrons, in agreement with experiment. The density of states available for d-hole decay is larger than that for the decay of excited electrons; however, the small overlap between d and sp states below the Fermi level increases the d-hole lifetime. The impact of d-hole dynamics on electron-hole correlation effects is also addressed.     

Quantum waves in noble metals

A theoretical study is presented of the effect of hole energy quantization in a dc magnetic field on microwave penetration through a noble-metal plate. It is shown that quantization results in strong oscillations of cyclotron absorption. Between the absorption peaks, the damping decreases sufficiently to enable propagation of unique quantum waves. Excitation of such waves in a metallic plate gives rise to sharp oscillations of its surface resistance with magnetic field. The shape of these oscillations is also very unusual. Fiz. Tverd. Tela (St. Petersburg) 41, 1354–1360 (August 1999)     

Many-body effects on effective lattice pseudopotential in metals

It is shown that processes involving the virtual excitation of plasmons contribute significantly to the vertex corrections to the effective lattice pseudopotential in metals.