Electron-Phonon Interactions Using Wannier Functions and the Projector-Augmented-Wave Method

Electron-phonon interactions play a pivotal role in simulating a wide variety of material properties. As a result, there is an ongoing effort to find more accurate and efficient algorithms to incorporate these interactions in materials simulations. To this end, we present an ab-initio density-functional-theory (DFT) approach for calculating electron-phonon interactions within the projector-augmented-wave (PAW) method. As the PAW method leads to a generalized eigenvalue problem, the resulting electron-phonon matrix elements lack some symmetries that are usually present for traditional all-electron formulations. To allow for efficient evaluation of physical properties, we use an interpolation scheme based on Wannier functions, with the required matrix elements constructed in a supercell using finite differences. While being inherently slower than most methods operating in reciprocal space, this approach has multiple advantages. Finally, we highlight results for the phonon-induced band-gap renormalization for polar and non-polar materials obtained from the implementation of this approach in the Vienna Ab-initio Simulation Package (VASP).

Phys. Rev. B 101, 184302