Comment by x2rj

GGA-DFT (+ some corrections) used here seems quite ok to me for this system. For more trust into this, I would like similar calculations with other methods to see how similar or different they are. LDA-DFT will most likely not be great (as in most cases), but I would be very interested in some DFT+GW calculations, even though LK99 might not be it's strength.