An efficient approach to electron-phonon coupling calculations of heterostructures within an all-electron framework

Overview & Synopsis

A major challenge in calculating electron-phonon coupling at interfaces from first principles is the prohibitive computational cost due to the large supercells involved. Here, we present an efficient approach, which builds the electron-phonon matrix of weakly bound heterostructures from the properties of the isolated layers. The two key ingredients, the dynamical matrices and the potential response, are constructed in two steps. In the expansion step, these quantities are folded from the unit cells onto the supercell through an exact Fourier mapping. In the addition step, the interatomic force constants and the potential responses of the heterostructure are assembled blockwise from the corresponding quantities of the isolated layers, neglecting the weak interlayer contribution. The method is implemented in the electron-phonon module of the all-electron full-potential code exciting, enabling efficient calculations of the electron-phonon self-energy. We demonstrate the approach for the phonon dispersion and spectral functions of bilayer WSe$_2$ and pyridine/MoS$_2$, in comparison with exact reference calculations.