so that λ l and U l determine the general shape and the sharpness of the partition function, respectively. Figure shows the contributions to the partition function for LiCl using D l = 1 for better comparability. The long-range interaction shows a weak transition when hitting the cross-over (dashed blue) where dipole-dipole interaction is replaced by higher order, more complex interactions. In contrast, the quadrupole (yellow) and octupole (green) terms show a fast decay at n R = 1.