Among the four used population methods, only the electrostatic potential (ESP) and fragment-based Hirshfeld (FBH) charge schemes consistently predict the expected trend in the fragment charge population, namely an enhanced CT with a shorter distance between two fragments. These values clearly show that the net transferred charge between Py and Au cluster is almost zero when the nearest distance between these two fragments is 5 Å, while it can be as large as 0.16 e -when the distance shortens to 3 Å in Py-Au 18 -V according to the FBH calculation. It suggests that the ground state charge migration between the Py molecule and Au cluster might also play an important role in the limited accuracy of our current QM/DIM Raman spectral simulations.