Hi,
density on symmetry elements usually displays artefacts and is difficult to interpret.
I've seen this rumor perpetuated so many times.. I think I can also say "Fourier maps show artifacts anywhere in the unit cell volume (including symmetry elements) that originate, for example, from: a) finite resolution and partial completeness of the data, b) errors in crystal structure model (model is always used as a source of phase information), c) measurement errors. These artifacts are difficult (and unnecessarily) to interpret in terms of atomic model.". Are symmetry elements somewhat special in this regard (that is one sees more artifacts on symmetry elements than anywhere else)? If this is the case, can someone provide convincing reasoning for this (not hand-waving!)? Thanks, Pavel