data resolution usage

Ethan A Merritt merritt at
Wed Nov 20 18:34:31 EST 1996

In article <9611201236.ZM24336 at>,
Robert D Scavetta <scavetta at XTREME.UCR.EDU> wrote:
>3.  For the low resolution cutoffs.  What is appropriate?  We have seen varied
>scripts where the low resolution cutoff was as low a 5 or as high as 50.  What
>cutoffs are appropriate for non-bulk solvent correction and bulk solvent
>correction in refinements?  What cutoff is appropriate for making maps?

Hah.  You may start some religious wars with this one :-).  
I'll stake out the high ground:

- The only low resolution cut-off should be that set by your data:
  That is, it should go to inifinity but in practice it won't because of 
  beam stop shadow, detector theta set to catch high resolution data, etc.

- Since you are including all this low-resolution data, you now need a
  bulk solvent model.  I prefer one based on the Babinet equations, as
  suggested by Dale Tronrud.   

- The above applies to BOTH refinement and map calculation.

You can find a discussion of the bulk solvent model and sample XPLOR
scripts for use in refinement on my web pages:

				Ethan A Merritt
				merritt at

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