Local Field Effect on Non-local Dielectric Screening of Two-Dimensional Interface Systems: A First-principles Study

Two-dimensional (2D) materials have provided platforms for exotic physics and emerging applications by forming van-der Waals interfaces. Non-local dielectric screening by substrates play an important role in modifying the quasiparticle properties of these interface systems. While several studies have been performed for the substrate screening of 2D materials, the underlying approximations and the connection between different methods have not been investigated in detail. We derived the effective polarizability of the interfaces from each monolayer sub-system, and showed its equivalence to sum over irreducible polarizability at the Random Phase Approximation level. We used this method to calculate prototypical 2D interface systems (heterojunctions and bilayers) and compared with explicit calculations. We compared different existing methods and discussed the local field effect on quasiparticle energies and absorption spectra. Our study shows good consistency between single layer calculations with effective interface screening and explicit interface calculations, and provides careful evaluation of approximations involved in studying substrate screening and interface quasiparticle properties.