I think it may well be a problem with the scaling. It is hard to get a reasonable estimate of the Wilson B at 3A - especially in a small cell. Look at the Log Graph plots - one associated with R factor gives you <Fobs> and <Fcalc> v resolution. They SHOULD overlap pretty well, but sometimes they dont and sometimes that is because the OVERALL B is badly estimated. Of course it is a function of the data but often hard to correct.. Eleanor
On 27 February 2014 16:26, Paul Paukstelis <shocksofmig...@gmail.com> wrote: > Greetings, > > We've been working on a number of related structures. Crystals are in P64 > with fairly small unit cell (40,40,55) and only diffract to around 2.5-3.0, > so we aren't working with a lot of reflections. For several of these data > sets the maps look very reasonable but Refmac refinement gives us unusually > low B-factors after either individual or grouped refinement (average of > around 10 A2 with some residues around 2 A2) while others are more 'normal' > (avg. 30-40) with very similar maps. I suspect something in data processing, > but I was wondering if there are opinions about what I should look for in > cases like this. Thanks in advance. > > --paul
