On 24 January 2012 15:23, Greg Costakes <gcost...@purdue.edu> wrote: > It would seem that you have a large model bias. Rule of thumb is to keep > R/Rfree within 5% of each other. If you find that the numbers > are separating during refinement you need to reduce the weighting factor > (dont use automatic) during refinement. What is your overall redundancy?
Reducing the AUTO weighting factor will have exactly the same effect as reducing the MATRIX factor: if you examine the Refmac code you'll see they both end up modifying the reflection weights. I find the default value of 10 for the AUTO factor much too high once the structure has been completely built and refinement is progressing. If a structure is already refined (e.g. protein-ligand work) I tend to start at WEIGHT AUTO 4 or even 2.5 and work down towards WA=1. This is the theoretically correct value (which is why I prefer to have the weight in units of WA instead of the completely arbitrary 'MATRIX' units), but usually it ends up being a little higher than 1 presumably because of some residual model errors. Cheers -- Ian
