Towards realistic calculations of polaron hopping in semiconductors from first principles

Polarons are localized carriers that emerge from the spontaneous deformation of the crystal structure due to electron-phonon interactions. The formation of these quasiparticles severely hampers carrier transport in many technologically important materials, such as ultra-wide-band-gap semiconductors, halide perovskites, and transition-metal oxides. Conventional supercell methods, commonly used to study polaron transport, are restricted to small polarons, meaning the transport properties of intermediate and larger scale polarons remain largely unexplored. Here, we report on our progress in implementing the nudged-elastic band method within the EPW code to investigate polaron-hopping mechanisms from first principles. Our method, based on the ab initio polaron equations, allows for large polarons to be modeled in systems containing tens of thousands of atoms, while maintaining the computational cost of primitive-cell calculations.