Hi
Just to clarify - for H32, a=b<>c (though you could have a=b=c within
measurement error), alpha=beta=90º, gamma=120º. Just having alpha=beta
<> gamma is necessary but not sufficient.
BTW, there's nothing wrong with alpha=beta=gamma=90º for the R
setting. It's just not required.
Sorry if this isn't clear - I'm just watching a very odd Olympic
opening ceremony, and it's quite distracting!
On 27 Jul 2012, at 21:09, Bernhard Rupp wrote:
H32 indicates the hexagonal obverse setting (as you list) for a R
centered trigonal cell, which is 3x larger than the primitive R32
cell indexed a=b=c, al=be=ga <> 90. Standard imho is the H32
setting, for which I will probably get flamed.
The relation between H and R cells is depicted here:
http://www.ruppweb.org/Garland/gallery/Ch5/pages/Biomolecular_Crystallography_Fig_5-29.htm
This has been discussed and is explained in the ccp4 tutorials and
doc afaik, where you can find more detailed info.
For proper format in a journal, I would suggest to adhere to the
format given in the ITC (International tables for Crystallography),
I.e. Bravais Italic, subscripted screw symbols. Note that this is
not the format you put it into most programs - their docs help.
You can also try my old space croup decoding program to see general
positions, operators, matrices and other useful stuff.
http://www.ruppweb.org/new_comp/spacegroup_decoder.htm
HTH, BR
-----Original Message-----
From: CCP4 bulletin board [mailto:[email protected]] On Behalf
Of Theresa Hsu
Sent: Friday, July 27, 2012 12:54 PM
To: [email protected]
Subject: [ccp4bb] Space group R32 and H32
Dear all
I have a confusion on the space group R32 and H32. For a cell
parameter of a = b not equal to c, alpha=beta, not equal to gamma,
is it considered as R32 or H32?
I tried searching the mail list archives but it does not help a
beginner crystallographer like me.
I also have another basic question. What is the correct way for
writing space groups? Is the Bravais lattice in italic and is there
space after that? Or it does not matter because both are used in
literature?
Thank you.
Harry
--
Dr Harry Powell, MRC Laboratory of Molecular Biology, MRC Centre,
Hills Road, Cambridge, CB2 0QH
