Plug the coordinates (x,y,z) and x+tx, Y+ty, z+tz) into the SF equation.
If the translation component along c is 0.5 say, then all the 00l
reflections for l=2n+1 will be absent.
Eleanor
Ronald E Stenkamp wrote:
Hi.
Non-crystallographic symmetry (NCS) doesn't apply to the entire
crystal, so how can it give rise to systematic absences? I know it
can give rise to systematically weak classes of reflections, but they
aren't entirely absent.
Ron
On Thu, 11 Dec 2008, Winter, G (Graeme) wrote:
One of the many facilities in pointless is to search for absences and
provide a list of likely spacegroup choices based on the results. It
includes adjustments for neighbouring spots to address one of
Eleanor's concerns. NCS can cause reflections to be systematically
absent too.
The program can be found on the ccp4 prerelease pages or on the
pointless ftp site.
Cheers,
Graeme
-----Original Message-----
From: CCP4 bulletin board [mailto:ccp...@jiscmail.ac.uk] On Behalf Of
Eleanor Dodson
Sent: 11 December 2008 09:41
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] About system absence in P4222?
劉家欣(NTHU) wrote:
Dear All:
We have a crystl with P4222 sg.
All statistics look fine.
However, there is a system absense in l axis.
Any body have experiences on that?
Any suggestions would be high appreciated.
jaishin
can you give more details, eg all reflections along the particular
axis..
Things like ice rings or overlapping intensity from a next neighbour
getting integrated inapropriately can cause anomalies..
Eleanor
