Dear Jiyuan, you can use MOLREP which takes into account pseudotranslations.
Good luck! Karsten > > Dear All, > > Recently I collected a data set to about 3.1 angstrom. Using Xtriage > program, I found a pseudo > translational symmetry on the c-axis. I noticed that overall diffraction > intensity is weak for this > dataset. I wonder if there are flaws in the crystal and I have difficulty > to solve the structure using > phaser. Has anyone seen similar cases and any comments and suggestions? > Thanks! > > Below is some analysis results from the Xtriage. > > Cell 102.937, 102.937, 203.059, 90, 90, 90, P422 > > ----------------------------------------------------------------------------------------- > Largest Patterson peak with length larger than 15 Angstrom > Frac. coord. : 0.000 0.000 0.350 > Distance to origin : 71.133 > Height (origin=100) : 48.451 > p_value(height) : 8.588e-05 > ---------------------------------------------------------- > Wilson ratio and moments > Acentric reflections > <I^2>/<I>^2 :2.568 (untwinned: 2.000; perfect twin 1.500) > <F>^2/<F^2> :0.728 (untwinned: 0.785; perfect twin 0.885) > <|E^2 - 1|> :0.850 (untwinned: 0.736; perfect twin 0.541) > Centric reflections > <I^2>/<I>^2 :3.953 (untwinned: 3.000; perfect twin 2.000) > <F>^2/<F^2> :0.577 (untwinned: 0.637; perfect twin 0.785) > <|E^2 - 1|> :1.111 (untwinned: 0.968; perfect twin 0.736) > > --------------------------------------------------------------------------------------------------- > NZ test (0<=z<1) to detect twinning and possible translational NCS > ----------------------------------------------- > | Z | Nac_obs | Nac_theo | Nc_obs | Nc_theo | > ----------------------------------------------- > | 0.0 | 0.000 | 0.000 | 0.000 | 0.000 | > | 0.1 | 0.126 | 0.095 | 0.293 | 0.248 | > | 0.2 | 0.239 | 0.181 | 0.394 | 0.345 | > | 0.3 | 0.327 | 0.259 | 0.471 | 0.419 | > | 0.4 | 0.401 | 0.330 | 0.521 | 0.474 | > | 0.5 | 0.464 | 0.394 | 0.557 | 0.520 | > | 0.6 | 0.518 | 0.451 | 0.597 | 0.561 | > | 0.7 | 0.569 | 0.503 | 0.635 | 0.597 | > | 0.8 | 0.613 | 0.551 | 0.660 | 0.629 | > | 0.9 | 0.648 | 0.593 | 0.683 | 0.657 | > | 1.0 | 0.679 | 0.632 | 0.706 | 0.683 | > ----------------------------------------------- > | Maximum deviation acentric : 0.071 | > | Maximum deviation centric : 0.052 | > | | > | <NZ(obs)-NZ(twinned)>_acentric : +0.054 | > | <NZ(obs)-NZ(twinned)>_centric : +0.035 | > > -------------------------------------------------------------------------------------- > L test for acentric data > using difference vectors (dh,dk,dl) of the form: > (2hp,2kp,3lp) > where hp, kp, and lp are random signed integers such that > 2 <= |dh| + |dk| + |dl| <= 8 > Mean |L| :0.490 (untwinned: 0.500; perfect twin: 0.375) > Mean L^2 :0.323 (untwinned: 0.333; perfect twin: 0.200) > The distribution of |L| values indicates a twin fraction of > 0.00. Note that this estimate is not as reliable as obtained > via a Britton plot or H-test if twin laws are available. > > ------------------------------------------------------------------------------- > Twinning and intensity statistics summary (acentric data): > Statistics independent of twin laws > <I^2>/<I>^2 : 2.568 > <F>^2/<F^2> : 0.728 > <|E^2-1|> : 0.850 > <|L|>, <L^2>: 0.490, 0.323 > Multivariate Z score L-test: 0.686 > > ------------------------------------------------------------------------------- > > Jiyuan Ke, Ph.D. > Research Scientist > Van Andel Research Institute > 333 Bostwick Ave NE > Grand Rapids, MI 49503 > > ------------------------------- Karsten Niefind University of Cologne Department of Chemistry Institute of Biochemistry Otto-Fischer-Str. 12-14 D-50674 Cologne Tel.: +49 221 470 6444 Fax: +49 221 470 3244
