Ab initio prediction of mode-selected surface electron-phonon coupling strengths probed by Helium atom scattering (HAS) from the 3x1-reconstructed Nb(001) surface oxide*

Using density-functional theory (DFT), we demonstrate that our calculations are able to accurately capture the surface electron-phonon physics at the (001) surface of niobium, the elemental superconductor with the highest critical temperature. The electron-phonon interaction is the fundamental mechanism determining the properties of conventional superconductors, and theoretical predictions of surface properties of superconductors are critically important as external fields penetrating at surfaces limit the material’s overall performance. In this talk, we report surface phonon dispersions and surface electron-phonon coupling strengths of the bare Nb(001) surface and the more complex Nb(001) surface with a long-ranged ordered, 3x1-reconstructed oxide layer. We present our ab initio predictions of the 3x1-O/NbO(001) system along with recent Helium atom scattering (HAS) which provide an experimental surface probe to directly measure mode-selected electron-phonon coupling strengths. The agreement between our DFT calculations and the HAS measurements on this non-trivial surface structure demonstrate the validity of our method and provide an exciting new application to predict surface electron-phonon coupling strengths.