Kay Diederichs wrote:
In this case the structure factors were deposited, but these do not
have a column for the anomalous signal. Re-refinement with these
structure factors was inconclusive.
If I could have downloaded the images, I could have investigated
this easily, because there's a large difference in the f" of those
two metals.
So to me access to images sometimes may help to answer a scientific question.
I would add a plea to those considering an image deposition system:
accept MAPS too!
At the very least it would be nice to see the initial and final maps
the crystallographer used. Even if I have the structure factors I'm
not necessarily an expert on the ins and outs of what someone had to
do to refine a twinned or otherwise troublesome structure, and I
don't want to have to learn the specific refinement program you used
to be able to reproduce the exact map you saw. (For very old
structures, it may no longer be possible to compile the specific
version of the refinement software on new processors/OSes, or someone
may have used a commercial refinement package.) And of course, there
are non-crystallographers who use structures and it is absurd to
expect them to learn x-ray refinement to see the relevant map for a
twinned structure that EDS couldn't process.
I love EDS. But even though it usually has a map for a given
structure, seeing the actual map generated by the crystallographer
who was the expert on the project would be better. Once a system is
designed that is large enough to handle images, maps would not
significantly increase the required storage space. I've poked a
couple people to suggest that even now the PDB ought to be accepting
maps.
--
-Eric
