Phonon Dispersion and Kohn Anomaues in the Alloy Cu0.84Al0.16

1989 ◽  
Vol 166 ◽  
Author(s):  
Henry Chou ◽  
S. M. Shapiro ◽  
S. C. Moss ◽  
Mark Mostoller
Keyword(s):  
Phonon Dispersion ◽  
Electron Interaction ◽  
Present System ◽  
High Symmetry ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Atomic Force ◽  
Complete Set ◽  
Pure Cu ◽  
Better Than

ABSTRACTWe have made detailed measurements of phonon frequencies along all high-symmetry directions on a large single crystal of Cu0.84Al0.16 at room temperature. Phonon frequencies were ascertained to better than ±0.03 meV. Inter-atomic force constants and vibrational density of states were calculated by performing a Born-von Karman analysis on the complete set of phonon dispersion curves. In contrast to the case of pure Cu, no evident Kohn anomaly (neither in the phonon dispersion itself nor in the derivatives) was observed near the expected wave vector q=2kF. The absence of Kohn anomalies in the present system could be due either to a smeared out Fermi surface or to the possibility that the electron-electron interaction which screens the inter-ionic potential is not the dominant interaction in the system; i.e. the existence of Kohn anomalies in these alloys may depend mainly on the details of the electron-phonon interaction.

Phonon renormalization of the electronic effective mass

1969 ◽  
Vol 47 (10) ◽  
pp. 1107-1116 ◽  
Author(s):  
J. P. Carbotte ◽  
R. C. Dynes ◽  
P. N. Trofimenkoff
Keyword(s):  
Effective Mass ◽  
Phonon Dispersion ◽  
Inelastic Neutron Scattering ◽  
Inelastic Neutron ◽  
Force Constants ◽  
Coupling Constant ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Phonon Renormalization ◽  
Pseudo Potential

We have made detailed first principle calculations of the phonon contribution to the renormalization of the electronic effective mass of a number of simple metals and alloys. The phonon frequencies and polarization vectors are generated from the interatomic force constants for the material. The force constants are taken from a Born – von Kármán analysis of the experimental phonon dispersion curves determined by inelastic neutron scattering. The electron–phonon interaction is treated using pseudo-potential theory which relates the coupling constant to the electron–ion form factor. For a spherical Fermi surface it is then possible to evaluate numerically the expression for the effective mass with no further approximations. We compare the results obtained with previous work when available and with experiment otherwise.

AB INITIO STUDY OF PHONON DISPERSION AND ELASTIC PROPERTIES OF L12 INTERMETALLICS Ti3Al AND Y3Al

2013 ◽  
Vol 27 (30) ◽  
pp. 1350224 ◽  
Author(s):  
N. ARIKAN ◽  
M. ERSEN ◽  
H. Y. OCAK ◽  
A. İYIGÖR ◽  
A. CANDAN ◽  
...  
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Phonon Dispersion ◽  
High Symmetry ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Phonon Dispersion Curves ◽  
Lattice Constants ◽  
Density Functional Perturbation Theory ◽  
Phonon Properties

In this paper, the structural, elastic and phonon properties of Ti 3 Al and Y 3 Al in L1 2( Cu 3 Al ) phase are studied by performing first-principles calculations within the generalized gradient approximation. The calculated lattice constants, static bulk moduli, first-order pressure derivative of bulk moduli and elastic constants for both compounds are reported. The phonon dispersion curves along several high-symmetry lines at the Brillouin zone, together with the corresponding phonon density of states, are determined using the first-principles linear-response approach of the density functional perturbation theory. Temperature variations of specific heat in the range of 0–500 K are obtained using the quasi-harmonic model.

Atomistic simulation of phonon dispersion for body-centred cubic alkali metals

2008 ◽  
Vol 86 (6) ◽  
pp. 801-805 ◽  
Author(s):  
Y Xie ◽  
J -M Zhang
Keyword(s):  
Cohesive Energy ◽  
Atomistic Simulation ◽  
Alkali Metals ◽  
Phonon Frequency ◽  
Phonon Dispersion ◽  
Atomistic Simulations ◽  
Phonon Dispersion Curves ◽  
Embedded Atom ◽  
Atomic Force ◽  
Good Agreement

Atomistic simulations of phonon dispersion for body-centred cubic alkali metals were carried out using the modified analytic embedded atom potentials. The expressions for atomic force constants are derived, the cohesive energy and elastic constants are calculated, and the phonon dispersion curves of Li, Na, K, Rb, and Cs are calculated along five principal symmetry directions. The calculated results are in good agreement with the available experiments. For all of the five alkali metals, in the same direction, a similar phonon dispersion curve is obtained in spite of the successive phonon frequency decreases for Li, Na, K, Rb, and Cs, which may be related to the atom mass increases or the cohesive energy decreases. PACS Nos.: 63.20.Dj, 71.20.Dg, 31.15.Ct

The lattice dynamics of crystalline carbon disulphide

1979 ◽  
Vol 57 (6) ◽  
pp. 851-859 ◽  
Author(s):  
P. J. Grout ◽  
J. W. Leech
Keyword(s):  
Lattice Dynamics ◽  
Phonon Dispersion ◽  
Carbon Disulphide ◽  
Pair Potential ◽  
Lattice Energy ◽  
High Symmetry ◽  
Phonon Dispersion Curves ◽  
Dipole Interactions ◽  
Rigid Molecule ◽  
Point Electric Dipole

The lattice dynamics of crystalline CS2 at 0 K is discussed within the rigid molecule, harmonic, and pair potential approximations. By including atom–atom point electric dipole interactions in a potential tailoring method introduced by Leech and Pawley equilibrium conditions are satisfied and excellent agreement is obtained between observed and calculated zero wave vector phonon frequencies and lattice energy. There is disagreement with other estimates of the magnitudes of some of the atom–atom interactions. Phonon dispersion curves for three high symmetry directions are presented.

Surface lattice dynamics and electron–phonon interaction in cesium ultra-thin films

2017 ◽  
Vol 19 (25) ◽  
pp. 16358-16364 ◽  
Author(s):  
D. Campi ◽  
M. Bernasconi ◽  
G. Benedek ◽  
A. P. Graham ◽  
J. P. Toennies
Keyword(s):  
Ultrathin Films ◽  
Density Functional ◽  
Phonon Dispersion ◽  
Phonon Interaction ◽  
Phonon Dispersion Curves ◽  
Helium Atom Scattering ◽  
Electron Phonon Interaction ◽  
Atom Scattering ◽  
Density Functional Perturbation Theory ◽  
Mass Enhancement

The phonon dispersion curves of ultrathin films of Cs(110) on Pt(111) measured with inelastic helium atom scattering (HAS) are reported and compared with density-functional perturbation theory calculations. The mass-enhancement factor is derived from the temperature dependence of the HAS Debye–Waller exponent.

scholarly journals Far-infrared absorption in cubic ZnS

1976 ◽  
Vol 54 (10) ◽  
pp. 1053-1060 ◽  
Author(s):  
E. A. Kwasniewski ◽  
E. S. Koteles ◽  
W. R. Datars
Keyword(s):  
Absorption Spectrum ◽  
Infrared Absorption ◽  
Phonon Dispersion ◽  
Far Infrared ◽  
Fourier Transform Spectrometer ◽  
High Symmetry ◽  
Phonon Density ◽  
Zone Boundary ◽  
Phonon Density Of States ◽  
Phonon Dispersion Curves

Far-infrared absorption in cubic ZnS due to single-phonon and two-phonon processes was measured with a high resolution, far-infrared Fourier transform spectrometer. A 14-parameter lattice dynamical shell model was fitted to phonon dispersion curves measured by Vagelatos et al. The two-phonon density-of-states calculated with these parameters was compared with the absorption spectrum. Two-phonon combinations and their locations in the Brillouin zone were identified with features of the absorption spectrum. Critical points were found on or near the zone boundary and not only at high symmetry points as suggested previously.

Phonon Properties of Americium Sulphide

2016 ◽  
Vol 28 ◽  
pp. 125-128
Author(s):  
Balwant Singh Arya ◽  
Mahendra Aynyas ◽  
Sankar P. Sanyal
Keyword(s):  
Present Model ◽  
Phonon Dispersion ◽  
Dispersion Curves ◽  
Phonon Interaction ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Breathing Motion ◽  
Shell Models ◽  
Phonon Properties

We have reported the phonon properties of AmS by using breathing shell models (BSM) which includes breathing motion of electrons of the Am atoms due to f-d hybridization. The phonon dispersion curves, density of states and specific heat calculated from present model. The calculated phonon dispersion curves of AmS are presented follow the same trend as observed in uranium sulphide. We have discussed the significance of this approach in predicting the phonon dispersion curves of this compound and examine the role of electron-phonon interaction.

scholarly journals Study of the Electron-Phonon Interaction in Metal Diborides MeB2 (Me = Zr, Nb, Ta, Mg) by Point-Contact Spectroscopy

2003 ◽  
Vol 17 (10n12) ◽  
pp. 657-666 ◽  
Author(s):  
I. K. Yanson ◽  
Yu. G. Naidyuk ◽  
O. E. Kvitnitskaya ◽  
V. V. Fisun ◽  
N. L. Bobrov ◽  
...  
Keyword(s):  
Phonon Dispersion ◽  
Point Contact ◽  
Band Model ◽  
Phonon Interaction ◽  
Metal Compounds ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Excess Current ◽  
Metal Diborides ◽  
Two Band Model

We review investigations of the electron-phonon interaction (EPI) in metal diborides MeB2 (Me = Zr, Nb, Ta, Mg) by point-contact (PC) spectroscopy. For transition metal compounds the PC EPI functions were recovered and EPI parameter λ ≲ 0.1 were estimated. The data are consistent with the measured surface phonon dispersion curves. The low λ value questions some reports about superconductivity in these compounds. Contrary, EPI in superconducting MgB2 films manifests also in the PC spectra itself by virtue of an elastic EPI contribution to the excess current determined by the energy dependence of the superconducting order parameter. To analyse the phonon features in the PC spectra of MgB2 a two-band model is exploited and the proximity effect in the k-space is suggested.

Superconductivity in Single Crystal Tl

1974 ◽  
Vol 52 (16) ◽  
pp. 1504-1509 ◽  
Author(s):  
P. T. Truant ◽  
J. P. Carbotte
Keyword(s):  
Single Crystal ◽  
Phonon Dispersion ◽  
Scattering Data ◽  
Electron Mass ◽  
Phonon Dispersion Curves ◽  
Electron Phonon Interaction ◽  
Gap Anisotropy ◽  
Crystal Transition ◽  
The Mean ◽  
Pure Single Crystal

We have used a model of the electron–phonon interaction in Tl which is consistent with neutron scattering data on the phonon dispersion curves as well as the superconducting tunneling data on the isotropic electron–phonon function α2(ω)F(ω) to explore the amount of anisotropy that can be expected in select properties of Tl. First the Fermi surface (FS) variation of the electron mass renormalization parameter λ(k) is determined. Then the superconducting gap Δ(k) is obtained for many k's on the FS. The mean square gap anisotropy is calculated. The pure single crystal transition temperature is obtained and compared with the dirty limit.

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