Hi Nat, okay. Looks like I missed this. Perhaps the data sets that I wish had Fiedel pairs didn't and this solidified my incorrect assumption(s) about pdb policy.
So Fiedel pairs are there when deposited. What about storage of images? Is it coming soon - it feels like that it is about time.... Lothar > On Fri, May 16, 2014 at 7:12 AM, <[email protected]> wrote: > >> Short of storing images, which is the ultimate preservation of primary >> information, I have always been puzzled by the fact that the PDB only >> stores >> unique reflections i.e. no Friedel pairs even when provided. Is this >> outdated >> perhaps ? I remember that my deposited SFs in the past where reduced to not >> contain Friedel pairs. If there had been a concern about increasing the >> storage space by actually less than twice the space for unique SFs, this >> may >> be invalid today and is still far less than the space required for images. >> However, it is possible that the information content in Friedel pairs is >> deemed insignificant compared to their extra costs. I for one would >> appreciate >> having access to Friedel pairs very much. >> > > They definitely store Friedel pairs! Maybe you're confused by the layout > of the mmCIF file, which (like MTZ) usually lists just the unique > (non-anomalous) indices, but with separate values for F+/F- when they are > available. I've been making extensive use of anomalous data depositions - > unfortunately there aren't as many as we would like, either because many > people do not realize that this is useful information even when the > experiment was not specifically looking for anomalous signal, or because > the complexity of PDB deposition discourages providing the most complete > data. > > An even more useful improvement would be to make deposition of unmerged > intensities straightforward - the JCSG does this somehow but it is > non-trivial for the average user. Hopefully this will also change soon. > > -Nat >
