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Difficult datasets: Difference between revisions
→optimizing the parameters for CORRECT
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* [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html#NBATCH= NBATCH]= (total rotation range)/45 ! to reduce the number of scale factors; the value of NBATCH is shown as NXBIN in CORRECT.LP for the ABSORB and DECAY correction; default is (total rotation range)/5. Other values, like (total rotation range)/60 or (total rotation range)/90 might also be tried. Try to match NBATCH with DELPHI (see above). | * [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html#NBATCH= NBATCH]= (total rotation range)/45 ! to reduce the number of scale factors; the value of NBATCH is shown as NXBIN in CORRECT.LP for the ABSORB and DECAY correction; default is (total rotation range)/5. Other values, like (total rotation range)/60 or (total rotation range)/90 might also be tried. Try to match NBATCH with DELPHI (see above). | ||
* [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html#CORRECTIONS= CORRECTIONS]= ABSORB ! don't try to correct for MODULATION and DECAY in scaling | * maybe [http://www.mpimf-heidelberg.mpg.de/~kabsch/xds/html_doc/xds_parameters.html#CORRECTIONS= CORRECTIONS]= ABSORB ! don't try to correct for MODULATION and DECAY in scaling because these may be poorly determined; however in general it helps to correct for them | ||
* FRIEDEL'S_LAW=TRUE unless the multiplicity is high. A clear sign that FRIEDEL'S_LAW=TRUE is required is that the CHI^2-VALUE OF FIT OF CORRECTION FACTORS is significantly below 1 (e.g. 0.5) | * FRIEDEL'S_LAW=TRUE unless the multiplicity is high. A clear sign that FRIEDEL'S_LAW=TRUE is required is that the CHI^2-VALUE OF FIT OF CORRECTION FACTORS is significantly below 1 (e.g. 0.5). If in doubt use the setting that maximizes ISa. | ||
== optimizing the parameters for XSCALE == | == optimizing the parameters for XSCALE == | ||
If you use XSCALE to merge several XDS datasets, you should make sure that you specify in XSCALE.INP the same values for NBATCH and CORRECTIONS as you do, in XDS.INP, for the CORRECT step. | If you use XSCALE to merge several XDS datasets, you should make sure that you specify in XSCALE.INP the same values for NBATCH and CORRECTIONS as you do, in XDS.INP, for the CORRECT step. | ||