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The first thing I would look at is the |E**2-1| number
in the intensity distributions.
This should indicate whether centrosymmetric or not.
0.736 for acentric and 0.968 for centric structures.

If this is not decisive in small molecules, suspicion
is in order, but w/o more stats it is hard to say.

BR


-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Bin
Li
Sent: Wednesday, August 02, 2006 7:47 PM
To: [email protected]
Subject: [ccp4bb]: Question about symmetry relationship

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Dear:
I have a question about symmetry relationship between two space groups.
In the literature, there is a compound AB4C2. It was refined with
I-4c2 space group and A, B, and C are at 4d, 16i and 8e sites, respectively.
I got a new compound AB4D2 which can be refined very well with high symmetry
space group, I4/mcm. In my compound A, B, and D are 4a, 16l, and 8h sites,
respectively. If I draw both structures,  they look same, except some bond
distances change.
The high symmetry space group is central symmetry and the another one in
non-central symmetry, but both have very similar Wyck positions. 
How do I figure out the symmetry relationship between these two structures?
Your help is highly appreciated!
Thank you for your time!

Best Regards!

Bin Li

Bin Li, Ph.D
Ames Lab., Iowa State University
Ames, IA, USA



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