Phonons and electron-phonon interaction by linear-response theory within the LAPW method

We present a calculation of phonon frequencies and electron-phonon coupling constants obtained from linear-response (LR) theory within the full-potential linearized augmented plane-wave (LAPW) method. We provide a formalism which allows us to treat LR theory in an all-electron manner. For the electron-phonon coupling matrix elements we include all correction terms, either arising due to the variational solution of the Kohn-Sham equations or due to the LAPW specific basis set. The method is applied to bcc sulfur and hcp beryllium. Our LR results are in excellent agreement with data obtained by the supercell approach.