Electron-phonon coupling strength of specific phonons from first principles LAPW calculations

Electron-phonon matrix elements, phonon linewidths and mode coupling strengths are being calculated for La2-xMxCuO4 (M=divalent cation, for paramagnetic x = 0.0 and for x = 0.15 in a rigid band picture) from first principles local density calculations. The change in potential due to a particular phonon mode is calculated from the difference of self-consistent one-electron potentials, and appropriate Fermi surface averages are carried out for selected modes, allowing us to obtain the phonon linewidth due to the electron-phonon interaction, and the corresponding coupling strength λ. The authors establish the numerical accuracy within the dual representation of the potential used in the linearized augmented plane wave (LAPW) method. Evaluations of phonon linewidths and mode coupling strengths are presented for Al and Nb and compared with previous information on these modes. The authors present preliminary results for the full matrix elements and coupling of the LA2CuO4 oxygen planar X-point breathing mode, and compare with a simpler approximation