Refinement involves many steps some of them do not guarantee monotonic decrease in R-factor. So what you observe is possible and in fact expectable just by the construction of the procedure.

If you would like to learn more

http://journals.iucr.org/d/issues/2012/04/00/ba5180/ba5180.pdf

and follow references therein.

So if you don't observe R-factor jumping up by more than 2-3% then I would say you have noting to worry about.

Pavel

On 4/21/15 7:20 PM, Smith Liu wrote:
Dear All,
 
Suppose I have a refine of 10 cycles, it get stablized from cycle 7. But sometimes I noticed that from the end of the cycle 10 to the end of the whole refinement, the stablization from 7 to cycle 10 can be destroyed a little, which makes me concern whether the final refinement can be regarded as convergent or not.
 
Will you please explain why the stablization from 7 to cycle 10 can be destroyed a little from the end of cycle 10 to the end of the whole refinement?
 
More critically, in the other situation, suppose I have a refine of 10 cycles, it get relatively stablized from cycle 5, from the end of cycle 5 to the end of cycle 10 the Rfree increase very slightly each cycle of the refine, which makes at the end of cycle 10 the Rfree is slightly higher than the Rfree at the start of the whole refinement. But from the end of cylce 10 to the end of the whole refinement, there is a slight decrease of Rfree, which makes the Rfree at the end of the whole refinement slightly lower than Rfree at the start of the whole refinement.
 
It seems to increase the cycles of the refinement would not help further.
 
Will you please explain the above phenomenon and to see whether the refine result can be acceptable, or do you have any suggestions for improvement?
 
Smith