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 and take into account the proper local symmetry. It is shown that the layered perovskite crystal symmetry generally favors strong electron-phonon interaction on the copper sites. The authors also estimate some non-RMTA effects.
 

Physical Review B, 42 366-79, 1990.