In the slides about the toy model and the question in that subchapter, there is concluded that the absolute value of the quadrupole energy splitting becomes smaller if the nucleus becomes smaller w.r.t. the electron cloud, so the splitting also gets bigger if the nucleus becomes bigger with respect to the same electron cloud. However, in the quantummechanical formula of the quadrupole splitting, the magnitude only depends on Q (so the deformation of the nucleus) and Vzz, so I would expect the magnitude to only become larger for larger deformation (this makes sense I think) if the EFG stays the same. Thus, does the magnitude of the electric quadrupole moment also become larger if the nucleus becomes larger, or is this only an effect because of the classical approximation?