Dear James,

yes, this reminds me of a problem long time ago: since the origin in P212121 is defined as the midpoint of non-intersecting screw axes (I hope that's right - I don't have the tables at hand), you have to add (1/4*a,1/4*c,1/4*b) after re-indexing, if I'm not mistaken.

Best regards,

Dirk.

Am 17.04.2009 um 13:06 schrieb James Stroud:

Update:

The pounding I am beginning to feel in my head is reminiscent of a pounding I felt while working in p43212 a while ago. I think this is an alternate origin issue. Now I just need to figure out how to redefine the origin.

James


On Apr 16, 2009, at 9:38 PM, James Stroud wrote:

Hello All,

I have two crystals (that I'll call "data set 1" and "data set 2") that seem to be isomorphic, but y and z are transposed between the two data sets. Reindexing data set 2 with the operators

h => -h
k => l
l => k

makes the axes match data set 1, but running MR with the previous data set 2 solution on the newly reindexed data set 2 yields a solution rotated 180 about z with respect to the data set 1 solution. What is the operation to reindex such that real space is rotated 180 about z? These are in P212121.

James


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Dirk Kostrewa
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