The Hopfield factor (electronic part of the electron-phonon coupling constant) is calculated in the Rigid-Muffin-Tin approximation (RMTA) for several perovskite high-Tc superconductors. Calculations were performed in the conventional 'spherical' approximation, as well as taking into account proper local symmetry. It is shown that the layered perovskite crystal symmetry general favors strong electron-phonon interaction on the copper site. The authors also estimate some for non-RMTA effects.
 

Physica C, 162-164 1347-8, 1989.