Non-adiabaticity in palladium hydride and deuteride

1978 ◽  
Vol 56 (5) ◽  
pp. 522-525 ◽  
Author(s):  
J. S. Brown
Keyword(s):  
Phonon Dispersion ◽  
Phonon Coupling ◽  
Optical Mode ◽  
Palladium Hydride ◽  
Electronic Screening ◽  
Electron Phonon Coupling ◽  
Optical Modes ◽  
Oppenheimer Approximation ◽  
Recent Formulation ◽  
Static Screening

We report the results of estimates of the breakdown of the Born–Oppenheimer approximation for the optical mode vibrations in PdHx and PdDx, using a recent formulation of the threshold for breakdown. Estimates are given of the degree of adiabaticity in these alloys as a function of the H(D) concentration x. We point out the result that for concentrations x for which the d-band has filled, the Born–Oppenheimer approximation may break down slightly, and there may be smaller corrections to static screening for lower concentrations. The estimate suggests that frequency-dependent electronic screening effects may not be totally negligible in a detailed treatment of the phonon dispersion of optical modes in these alloys, and other properties which may be affected by the electron–phonon coupling.

Kohn Anomalies in Graphite and Nanotubes

2004 ◽  
Vol 858 ◽  
Author(s):  
S. Piscanec ◽  
M. Lazzeri ◽  
A. C. Ferrari ◽  
F. Mauri ◽  
J. Robertson
Keyword(s):  
Fermi Surface ◽  
Brillouin Zone ◽  
Phonon Dispersion ◽  
Anomalous Behaviour ◽  
Phonon Coupling ◽  
Reduced Dimensionality ◽  
Electron Phonon Coupling ◽  
Atomic Vibrations ◽  
Semiconducting Nanotubes

ABSTRACTAtomic vibrations are partially screened by electrons. In a metal this screening can change rapidly for vibrations associated to certain points of the Brillouin zone, entirely determined by the shape of the Fermi surface. The consequent anomalous behaviour of the phonon dispersion is called Kohn anomaly. Graphite is a semimetal. Nanotubes can be metals or semiconductors. We demonstrate that two Kohn anomalies are present in the phonon dispersion of graphite and that their slope is proportional to the square of the electron-phonon coupling. Metallic nanotubes have much stronger anomalies than graphite, due to their reduced dimensionality. Semiconducting nanotubes have no Kohn anomalies.

scholarly journals Through a Lattice Darkly: Shedding Light on Electron-Phonon Coupling in the HighTcCuprates

2010 ◽  
Vol 2010 ◽  
pp. 1-23 ◽  
Author(s):  
D. R. Garcia ◽  
A. Lanzara
Keyword(s):  
Phase Diagram ◽  
Phonon Dispersion ◽  
Nodal Point ◽  
Phonon Coupling ◽  
Spin Orbital ◽  
Angle Resolved Photoemission Spectroscopy ◽  
X Ray Scattering ◽  
Electron Phonon Coupling ◽  
New Perspective

With its central role in conventional BCS superconductivity, electron-phonon coupling appears to play a more subtle role in the phase diagram of the high-temperature superconducting cuprates. Their added complexity due to potentially numerous competing phases, including charge, spin, orbital, and lattice ordering, makes teasing out any unique phenomena challenging. In this review, we present our work using angle-resolved photoemission spectroscopy (ARPES) exploring the role of the lattice on the valence band electronic structure of the cuprates. We introduce the ARPES technique and its unique ability to the probe the effect of bosonic renormalization (or “kink”) on near-EFband structure. Our survey begins with the establishment of the ubiquitous nodal cuprate kink leading to how isotope substitution has shed a critical new perspective on the role and strength of electron-phonon coupling. We continue with recently published work connecting the phonon dispersion seen with inelastic X-ray scattering (IXS) to the location of the kink observed by ARPES near the nodal point. Finally, we present very recent and ongoing ARPES work examining how induced strain through chemical pressure provides a potentially promising avenue for understanding the broader role of the lattice to the superconducting phase and larger cuprate phase diagram.

Size dependence of surface optical mode and electron–phonon coupling in ZnO nanocombs

2012 ◽  
Vol 407 (17) ◽  
pp. 3510-3514 ◽  
Author(s):  
Donghua Fan ◽  
Rong Zhang ◽  
Yufu Zhu ◽  
Huiren Peng
Keyword(s):  
Size Dependence ◽  
Phonon Coupling ◽  
Optical Mode ◽  
Surface Optical ◽  
Electron Phonon Coupling

scholarly journals Phonon Dispersion and Electron-Phonon Coupling inMgB2andAlB2

2001 ◽  
Vol 86 (25) ◽  
pp. 5771-5774 ◽  
Author(s):  
K.-P. Bohnen ◽  
R. Heid ◽  
B. Renker
Keyword(s):  
Phonon Dispersion ◽  
Phonon Coupling ◽  
Electron Phonon Coupling
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