Space group determination: Difference between revisions

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== Influencing the selection by XDS ==
== Influencing the selection by XDS ==
=== new parameters ===
=== parameters ===
The automatic choice is influenced by a number of decision constants that may be put into XDS.INP but which have defaults as indicated below:
The automatic choice is influenced by a number of decision constants that may be put into XDS.INP but which have defaults as indicated below:
* MAX_CELL_AXIS_ERROR= 0.03      ! relative deviation of unconstrained cell axes from those constrained by lattice symmetry
* MAX_CELL_AXIS_ERROR= 0.03      ! relative deviation of unconstrained cell axes from those constrained by lattice symmetry
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* MAX_FAC_Rmeas= 2.0              ! factor to multiply the lowest R<sub>meas</sub> with to still be acceptable
* MAX_FAC_Rmeas= 2.0              ! factor to multiply the lowest R<sub>meas</sub> with to still be acceptable


The user may experiment with adjusting these values to make the automatic mode of space group determination more successful. However, it is much easier to just input the space group and cell parameters that the user thinks are correct.
The user may experiment with adjusting these values to make the automatic mode of space group determination more successful. For example, if the crystal diffracts weakly, all R<sub>meas</sub> values will be high and no valid decision can be made. In this case, I suggest to use e.g.
TEST_RESOLUTION_RANGE= 50.0 10.0


=== alternative indexing ===
=== alternative indexing ===
2,684

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