On the errors in molecular dipole moments derived from accurate diffraction data.

The error in the molecular dipole moment as derived from accurate X-ray diffraction data is shown to be origin dependent in the general case. It is independent of the choice of origin if an electroneutrality constraint is introduced, even when additional constraints are applied to the monopole populations. If a constraint is not applied to individual moieties, as is appropriate for multicomponent crystals or crystals containing molecular ions, the geometric center of the entity considered is a suitable choice of origin for the error treatment.