$\mathit{\text{Ab}}\mathit{\text{initio}}$ electron-phonon coupling theory of elastic helium atom scattering

We propose a fully $\mathit{\text{ab}}\mathit{\text{initio}}$ approach to predicting thermal attenuation in elastic helium atom scattering amplitudes, validated through strong agreement with experiments on Nb(100) and (3$\times$1)-O/Nb(100) surfaces. Our results reveal the relative contributions from bulk, resonant, and surface phonon modes, as well as from different surface mode polarizations, providing insights into differences between smooth and corrugated surfaces. These findings advance understanding of surface dynamics and electron-phonon coupling, laying groundwork for future studies on surface superconductivity.