Ab initio prediciton of vacuum propagating electronic states: a truncated Green's function approach for use with plane-wave density-functional theory software

Plane-wave density functional theory (DFT) has proven to be a powerful tool in modern computational physics for the ab initio calculation of the electronic structure of solids, surfaces, and molecules. A substantial drawback for systems lacking periodicity in at least one direction is the interaction of long-range functions with periodic images. While Coulomb truncation methods have been developed to limit simple charge-image effects, Kohn-Sham orbital-mediated electronic interactions between images become a major source of error when calculating scattering, vacuum-propagating, states. We will present a new, truncated Green's Function approach to break periodicity along one or more dimensions in such a way that is compatible with standard plane-wave DFT pseudopotential codes, yet allows accurate calculation of scattering states at arbitrary energies. Finally, as an application, we will present transmission, reflection, and photoemission predictions for a variety of 2D materials including transition-metal dichalcogenides (TMDs).