> Is it reasonable to refine occupancy in phenix at 2.2 A resolution?
Implementations may differ, but imgo refining occupancy at 2.2A
resolution is not very reasonable under most circumstances, as it will
correlate strongly with the B-factor. A reasonable approach might be to
fix occupancy at different levels and get a series of refined models.
Then you look at (i) B-factor behavior and see at what occupancy it
matches the surrounding atoms and (ii) difference density (my
unsubstantiated theory is that if you plot it against occupancy it
should have a central flat region where B-factors are capable of
compensating and two linear regions on extreme ends which should allow
to extrapolate the true value.
Refmac does occupancy refinement. It's quite fast, so you may try
randomizing the initial value and get some idea about convergence.
Cheers,
Ed.
--
Oh, suddenly throwing a giraffe into a volcano to make water is crazy?
Julian, King of Lemurs
