Cad will do this correctly Reflection utilitied - merge mtz ( rather confusing job title - sorry..) mtz in - the P4121.mtz data Output - P41212-ext.mtz
Defne mtz output Select define limit for refl;action by Laue code select P1 then you will get a list of all P1 reflections with phases correctly modified. If you really want to work in P1 you will need to change the space group in P41212-ext.mtz Easiest way is mtzutils hklin1 P4121-ext.mtz hklout P41212-ext-symP1.mtz SYMM P1 end DONT change the G of P41212.mtz before doing the extension - the program needs the P41212 sym ops to change the phases correctly.. If you want the coordinates extended too use pdbset to get a P1 set of cds.. (Coordinate utilities Edit pdb select pdbset and "generate chains by symmetry operators" eleanor Eleanor On 12 April 2012 06:51, Henning Stahlberg <henning.stahlb...@unibas.ch>wrote: > Hi Everybody, > > I am working in a P4212 plane group, which is a p4 symmetric structure > with a screw axis in addition. My map has in the unit cell two 4-fold > symmetric structures, one if which is upside-down with respect to the other > one. If using expand in sftools, then the resulting map is p4 symmetrized > in the center between two p4-symmetric structures, which is wrong. This is > probably the phase origin problem referred to here: > http://www.ccp4.ac.uk/dist/html/sftools.html#expand > > Would anybody have a suggestion how I can expand the p4212 MTZ file to > full p1, but with properly respecting the symmetry phase origin? > > My illiterate guess would be to either > 1) shift the phase origin in the p4212 MTZ file by (180.0;0.0); then use > sftools with "expand 1" to create the full reflection sets in p1; then > shift back by (180.0;0.0); or > 2) use sftools with the command "expand 1", and then modify (invert?) the > phases of the reflections in the quadrants that have wrong phases. > > In option 1) I am not sure if it is possible to shift phase origin, while > staying in p4212 symmetry. How could I do that? > In option 2) I would probably get into deep water the next time I work > with another symmetry, like p6212, or p2121, where I would have to deal not > with quadrants but with triangles of 60deg angle? > > Any suggestions would be highly appreciated. > > All the best, > > Henning. > > Henning Stahlberg, PhD > Prof. for Structural Biology, C-CINA, Biozentrum, University Basel > Mattenstrasse 26 | D-BSSE | WRO-1058 | CH-4058 Basel | Switzerland > http://c-cina.org | Tel. +41-61-387 32 62 >
