[ccp4bb]: refmac5 and RNA refinement problem

[<wgscott@chemistry.ucsc.edu>]

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I am very new to refmac as I was getting frustrated refining an RNA 
molecule in CNS and have found that Refmac5 seemed to be a good 
alternative.

However I am now finding that the bond between the phosphorus atom of 
one nucleotide and the O3' of the next nucleotide appears to have no
distance restraint that keeps it sensible.  Moreover, the worst cases 
always seem to be those in which the O3' is on a U nucleotide.

Any suggestions for how I ought to deal with this?  (I've been refining 
along the lines of Example 5 in the CCP4-4.2 documentation for Refmac5.)

Thanks in advance.

Bill Scott