[buster-discuss] special position in refine v1.10.0

[wtempel]

Hello,
I experience problems with a sodium ion on a special position. This
special position lies on a two-fold axis and I set the occupancy to
0.5. With or without specifying -constant_dist, the ion will drift
away from this position even though it has been placed very close (as
precisely as visually possible) to its (special) position. As a
workaround I have considered fixing the ion in its position, but do
not know how to specify atoms that should remain fixed during
refinement. Any ideas out there?
Thank you,
Wolfram Tempel