Dear Anita,
To use the input value of the mosaic spread rather than the
refined value during cell refinement or integration, use the keywords:
POSTREF FIX MOSAIC
The mosaicity will be refined, but the input value and not the refined
value will be used for processing.
There are instances when the mosaic spread refinement is not well
behaved. If the initial cell (from autoindexing) is rather inaccurate
(eg due to an incorrect crystal to detector distance) then it can
refine towards zero during cell refinement. It can also refine to very
small (or negative) values if the spots are badly split. Refining to
values that are too large is less common, but if you have two
overlapping lattices then this could perhaps explain it.
Apologies if the current documentation is not clear on this point.
Best wishes,
Andrew Leslie
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