Just shift the origin in the C2 group and you get C21. Since they're
redundant, only one is named, the simpler one.
On Tue, 11 Sep 2007, wu donghui wrote:
> Dear all,
>
> I just get into touch with x-ray crystallography, and I made a "big"
> discovery that there is no C21 space group in monoclinic system, which
> system only contains P2, P21 and C2 groups. Even in the entire 65 chiral
> space group, there is no space for this group. I made an assumption that if
> there is C21 space group in monoclinic system, then the four equivalent
> point position could be described as: x, y, z; 1/2+x, 1/2+y, z; -x, 1/2+y,
> -z; 1/2-x, y, -z. However when I check the 65 chiral space group, no one is
> compatible with this equivalent positions. And I know I must make some
> mistakes. Unfortunately I can not find where the mistake stems from. I have
> to recourse to our expert community for your generous help.
> All replies are warmly welcomed and appreciated.
>
> Best regards,
>
> Donghui
>
--
========================================================================
Robert M. Sweet E-Dress: [log in to unmask]
Group Leader, PXRR: Macromolecular ^ (that's L
Crystallography Research Resource at NSLS not 1)
http://px.nsls.bnl.gov/
Biology Dept
Brookhaven Nat'l Lab. Phones:
Upton, NY 11973 631 344 3401 (Office)
U.S.A. 631 344 2741 (Facsimile)
========================================================================
|