2. Your First Round of Refinement with Shelxl

Shelxpro outputs some values for certain instructions that may or may not be appropriate to your experiment.

The header of the newly created .ins file should look like this:

There are things here that you may want to check on before starting refinement:

Shelxpro Default Output: Consider changing it to: Quirk:
CGLS 10 
(§ 7.6)
CGLS 10 -1 Add the -1 to implement the use of a test set for Rfree.
SHEL 10 0.1 
(§ 7.2)
SHEL x y x and y are your low and high resolution limits.  You are best advised to start with a higher value of y (lower high resolution limit) so that your initial refinement goes more quickly.
CONN 0 OH2_### > LAST 
(§ 7.4)
  ### refers to the first water residue number.  This instruction means that the connectivity of all atoms numbered higher than ### have a connectivity of zero.  This is a problem if you have ligands, ions, etc. that are numbered above ###.  The best thing to do is make sure that your waters are the highest numbered atoms in your atom list before running Shelxpro.
TEMP 20 
(§ 7.7)
TEMP -180 If you've collected data at anything other than room temperature, this will help slightly.

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