The Effects of the Electron-Phonon Interaction on the Vibrational Anomalies and Polymorphism in Titanium

1997 ◽  
Vol 491 ◽  
Author(s):  
J. L. Gavartin ◽  
D. J. Bacon
Keyword(s):  
Molecular Dynamics ◽  
Low Temperatures ◽  
Tight Binding ◽  
Phonon Interaction ◽  
Frequency Shifts ◽  
Electron Phonon Interaction ◽  
Electron Density Of States ◽  
Ω Phase ◽  
Molecular Dynamics Methods ◽  
Lattice Distortions

AbstractWe apply the frozen phonon and molecular dynamics methods within the semiempirical orthogonal tight-binding framework to study the anomalous behaviour of the (0001) optical longitudinal (LO) and transverse (TO) phonons in the low temperature hep phase of Ti, and the ⅔[111]L and ½[110]T1 phonons in the high temperature bec phase. We demonstrate that, in agreement with previous findings in Zr, the anomalous thermal frequency shifts in hep Ti are related to the strong coupling of the electron density of states (DOS) to the particular lattice distortions. The distortions along the bec ⅔[111]L and ½[110]T1 phonons also significantly affect the DOS, resulting in the instability of these modes at low temperatures and triggering the bcc-hep and bcc-ω phase transformations.

ELECTRON-PHONON INTERACTION AND SUPERCONDUCTIVITY IN OXIDE SUPERCONDUCTORS La2−xSrxCuO4

1993 ◽  
Vol 07 (01n03) ◽  
pp. 182-185
Author(s):  
M. SHIRAI ◽  
T. KINOSHITA ◽  
K. MOTIZUKI
Keyword(s):  
Tight Binding ◽  
Wide Energy Range ◽  
Oxide Superconductors ◽  
Tunneling Conductance ◽  
Eliashberg Equations ◽  
Phonon Modes ◽  
Phonon Interaction ◽  
Characteristic Structure ◽  
Electron Phonon Interaction ◽  
Wide Energy

Effects of electron-phonon interaction on lattice dynamics in oxide superconductors La 2−x Sr x CuO 4 (LSC) are studied microscopically on the basis of the tight-binding band fitted to the first principle band. Breathing-type vibrations of oxygen atoms in the CuO 2 plane are renormalized significantly at around (π/a, π/a, 0) and (π/a, 0, 0) due to strong dependences of the electron-phonon interaction on wavevectors and phonon modes. In the framework of the usual phonon-mediated pairing mechanism, superconducting properties, such as transition temperatures and tunneling spectra, are studied by solving isotropic Eliashberg equations. The spectral function α2F(ω) has a characteristic structure over a wide energy range below 85 meV. The tunneling conductance d I/ d V and its derivative d 2I/ d V2 calculated have prominent peaks below 40 meV, which show good correspondences to those observed by recent tunneling experiments.

scholarly journals Electron-phonon interaction within classical molecular dynamics

2016 ◽  
Vol 94 (2) ◽  
Author(s):  
A. Tamm ◽  
G. Samolyuk ◽  
A. A. Correa ◽  
M. Klintenberg ◽  
A. Aabloo ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Classical Molecular Dynamics

Spectroscopic Ellipsometry and Band Structure of Si1–yCy Alloys Grown Pseudomorphically on Si (001)

1995 ◽  
Vol 379 ◽  
Author(s):  
Stefan Zollner ◽  
Craig M. Herzinger ◽  
John A. Woollam ◽  
Subramanian S. Lyer ◽  
Adrian P. Powell ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Low Temperatures ◽  
Molecular Beam ◽  
Tight Binding ◽  
Analytical Line ◽  
Virtual Crystal Approximation ◽  
Line Shapes ◽  
Dynamics Simulations ◽  
Derivatives Of

ABSTRACTWe have measured the dielectric functions of three Si1−yCy, alloys layers (y ≤1.4%) grown pseudomorphically on Si (001) substrates using molecular beam epitaxy at low temperatures. From the numerical derivatives of the measured spectra, we determine the critical point energies E′0 and E1 as a function of y (y ≤ 1.4%) using a comparison with analytical line shapes and analyze these energies in terms of the expected shifts and splittings due to negative hydrostatic pressure, shear stress, and alloying. Our data agree well with the calculated shifts for El, but the E′0 energies are lower than expected. We discuss our results in comparison with recent tight-binding molecular dynamics simulations by Demkov and Sankey (Phys. Rev. B 48, 2207, 1993) prediciting a total breakdown of the virtual-crystal approximation for such alloys.

ELECTRON-PHONON INTERACTION, LATTICE DYNAMICS AND SUPERCONDUCTIVITY OF LAYERED TRANSITION-METAL DICHALCOGENIDE NbS2

1993 ◽  
Vol 07 (01n03) ◽  
pp. 188-192 ◽  
Author(s):  
Yoshimasa NISHIO ◽  
Masafumi SHIRAI ◽  
Naoshi SUZUKI ◽  
Kazuko MOTIZUKI
Keyword(s):  
Transition Temperature ◽  
Lattice Dynamics ◽  
Tight Binding ◽  
Transition Metal Dichalcogenide ◽  
Superconducting Transition ◽  
Lattice Instability ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Order Of Magnitude ◽  
Layered Transition Metal

Lattice dynamics of NbX 2( X = S , Se ) is studied by taking account of electron-phonon interaction derived microscopically on the basis of the realistic tight-binding bands fitted to the first-principle bands of NbX 2. Remarkable frequency renormalization of Σ1 phonon mode around [Formula: see text] is caused due to characteristic wave-vector and mode dependences of the electron-phonon interaction as well as nesting effect of Fermi surface. It is also shown that the short range force constant for neighboring X ions on different X-layers in the same X-Nb-X sandwich determines primarily whether lattice instability occurs ( NbSe 2 case) or does not occur ( NbS 2 case). By using the electron-phonon interaction and the lattice dynamics obtained for NbS 2 we have calculated the spectral function α2F(ω) and determined superconducting transition temperature T c by solving the linearlized Eliashberg equation. Renormalization of phonon frequencies due to the eletron-phonon interaction raises considerably the transition temperature and the obtained value of T c agrees in order of magnitude with the experimental data.

Systematic tight-binding study of the electron-phonon interaction in metals

Physica B+C ◽  
1985 ◽  
Vol 135 (1-3) ◽  
pp. 473-476 ◽  
Author(s):  
J.L. Fry ◽  
G. Fletcher ◽  
P.C. Pattnaik ◽  
D.A. Papaconstantopoulos
Keyword(s):  
Tight Binding ◽  
Binding Study ◽  
Phonon Interaction ◽  
Electron Phonon Interaction
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