Note that the magnitude of the charges differs between the Hirshfeld and CM5 results for the -OH2 group. The CM5 method is considered a more reliable estimate than the Hirshfeld method (Marenich and others, 2012) and what is crucial is the direction of change. The sums of the charges are non-zero and slightly negative, whereas the molecule is expected to be neutral. This is likely due to a numerical artifact because the electron density distribution disperses the charges throughout the 90-atom system.