In this paper we calculate the electron-phonon coupling of the newly-discovered superconductor LaO1−xFxFeAs from first-principles, using Density Functional Perturbation Theory. For pure LaOFeAs, the calculated electron-phonon coupling constant λ=0.21 and logarithmic-averaged frequency ωln=206K, give a maximum Tc of 0.8 K, using the standard Migdal-Eliashberg theory. For the F−doped compounds, we predict even smaller coupling constants, due to the strong suppression of the electronic Density of States at the Fermi level. To reproduce the experimental Tc=26K, a 5-6 times larger coupling constant would be needed. Our results indicate that electron-phonon coupling is not sufficient to explain superconductivity in the newly-discovered LaO1−xFxFeAs superconductor, probably due to the importance of strong correlation effects.
@article{arxiv.0803.2703,
title = {Is LaO$_{1-x}$F$_x$FeAs an electron-phonon superconductor ?},
author = {L. Boeri and O. V. Dolgov and A. A. Golubov},
journal= {arXiv preprint arXiv:0803.2703},
year = {2008}
}