Good to know, thanks. I was actually wondering about this recently.
On Sun, Jan 1, 2012 at 1:14 PM, Dima Klenchin <klenc...@facstaff.wisc.edu>wrote: > I've seen this happening to water molecules as well (in a somewhat >> unpredictable fashion). In the latest refmac versions, you can try >> harmonic restraints, although these will only slow down the atom drift, >> as the target position is updated every cycle. >> >> Perhaps you can use distance restraints against a dummy atom to fix the >> metal ion in place. >> > > Thanks, Ed! > > Just in case anyone else has the same issue: > > With Garib's help, I have forced the atom into its position by using > external distance restrains of zero length against the same > symmetry-related atom. The cause is unclear because the same program > handles special positions in another structure just fine. Here is the exact > command I used: > > EXTERNAL DISTANCE first chain M residue 3 atom MN - > second chain M residue 3 atom MN value 0.0 sigma 0.00 symm Y > > Occupancy set manually to 0.5. > > - Dima >
