A limitation of approaches that avoid direct modeling of the interface is that they cannot describe phenomena, such as band bending and the penetration of states from one material into the gap of the other in the vicinity of the interface. Modeling these phenomena requires a sufficient number of layers to span their length-scale. We also note that it has been shown that structural relaxation at the interface can have a significant effect on the band alignment, 104 and this is indeed the case for the interfaces studied here, as discussed below.