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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