It is well known that the X-ray diffraction data contain much more information than that described by the standard electron density model, used by almost all refinement software. To make use of this information several methods have been proposed, of which the most popular ones are multipolar model of electron density distribution (Hansen-Coppens model) or the methods combining the experimental data with the quantum calculations. Such approaches proved to be successful for small molecules, showing the importance of acquiring good and high-resolution data.
Examples of such analyses will be presented, together with the tools used and the perspectives for further advances. Some attempts to transfer such models to the macromolecules–proteins and nucleic acids have been made, but this is another level of complications, caused by the lack of high-resolution data, the presence of solvent molecules, multiple conformations and by the non-centrosymmetricity of the objects of the studies. There are very few examples of successful results which are described, and the question included in the title – if these results are worth the efforts – will be addressed. Unfortunately, no ultimate answers will be presented.