▎ 摘　　要

Understanding the modulation of the electronic coupling in molecular crystals, and two-dimensional materials is crucial from a fundamental point of view as well as for the development of organic electronics. In this work, we present a first-principles quantum-mechanical method for the calculation of the electronic coupling (or transfer integrals) between fragments or layers, using density functional theory with periodic boundary conditions (DFT-PBC) within the Gamma-point approximation. This method is applied to two periodic systems: crystalline pentacene and a bilayer graphene film. For the former system, we find that the inclusion of the solid environment affects the interfragment electronic couplings) with changes of the order of 10%. However, we confirm the qualitative trends obtained with the "isolated molecular dimer" model. For the graphene film, we show how the interlayer coupling changes with the relative position of two pi-stacked layers. Interestingly, we find that particle-particle coupling is large even for configurations that are not perfectly stacked.