On Saturday, 04 October 2014 10:26:51 AM Kay Diederichs wrote:
> I do agree that in your use case it may be helpful to order a<b<c as
> long as the symmetry is unknown. I also do understand that the H-M
> symbols allow to describe the different settings, but this is a level of
> complication that is not necessary to understand for todays's typical
> crystallographer, because fortunately e.g. the C121 setting is
> practically uniformly used (and chosen by POINTLESS, as far as I
> understand) to represent C2 crystals.
I will not stick my nose into the main discussion here,
but I will note that this part of it is incorrect.
POINTLESS uses the IUCr convention to select either C2 or I2
depending an the beta angle.
This caused me great confusion when I first encountered it, not least
because a very slight variation in the refined beta angle can change the
spacegroup in the output file.
Ethan
--
mail: Biomolecular Structure Center, K-428 Health Sciences Bldg
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