Phonon dispersion and electron-phonon interaction for YBa 2 Cu 3 O 7 from first-principles calculations

Abstract
We present a first-principles investigation of the lattice dynamics and electron-phonon coupling of the high-Tc superconductor YBa2Cu3O7 within the framework of density functional perturbation theory using a mixed-basis pseudopotential method. The calculated phonon dispersion curves are in excellent agreement with Raman, infrared and neutron data. Calculation of the Eliashberg function α2F leads to a small electron-phonon coupling λ = 0.27 in disagreement with earlier approximate treatments. Our calculations strongly support the view that conventional electron-phonon coupling is not an important contribution to superconductivity in high-Tc materials.
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