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Hello Peter-
Is it possible that you are shooting close to an axis? If you are shooting near parallel to one of the crystal axis, you will get values that are reasonable for 2 cell lengths but extremely low values for the third. Try indexing a frame that is say 30 degrees into the collection and see if you have the same problem. If the crystal is aligned with one axis along the direction of the x-ray beam, and the goniometer rotating around that direction then you may likely have to reorient the crystal and recollect the data. This may be why you it hasn't worked for several images. Outside of beam center, i think this is something for you to have a look at.
-Todd
-----Original Message-----
From: CCP4 bulletin board [[log in to unmask]] on behalf of Peter Hsu [[log in to unmask]]
Sent: Monday, February 20, 2012 6:28 PM
To: [log in to unmask]
Subject: [ccp4bb] HKL2000 indexing problem
Hi all,
I recently collected a data set off a single crystal and have had problems with indexing it. Every time I go pick peaks for indexing it constantly picks peaks that are just slightly off the actual peak. After indexing, it would always be that 2 of the 3 cell dimensions would be fairly normal, while the 3rd would have some impossible value such as 1.
On some other occasions if it manages to pick peaks properly, and every time I go to index it, it gives back an error that I don't have enough peaks picked to index (picked nearly 500).
I've tried using a number of different images to index from and have run into the same problem.
Has anyone else run into these problems? Does anyone have any idea what might be wrong w/my dataset and/or crystal?
Thanks in advance for any insight,
Peter
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