Phonon dispersion and electron-phonon interaction for YBa2Cu3O7 from first-principles calculations

We present a first-principles investigation of the lattice dynamics and electron-phonon coupling of the high-T-c 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 alpha(2)F leads to a small electron-phonon coupling lambda = 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-T-c materials.