[phenixbb] Implementation of French & Wilson data correction?
pafonine at lbl.gov
Mon Feb 28 17:31:31 PST 2011
> A little off-topic, but will phenix implement MLI (maximum likelihood
> intensity target)?
eventually. The formulas are there, someone just needs to get enough of
motivation to spend a couple of days and code them thus making available
Once this is done, then there will be another set of troubles to deal with:
- what to use to compute R-factors: Iobs or Fobs? If Fobs, then in turn
you will go back to the original problem of converting I to F. If Iobs,
then I bet a number of people will scream that they want to see the
R-factors computed the "usual way" (using Fobs, that is).
- Same questions about computing the maps.
> I heard that MLI target gives a good result because MLI handles
> negative intensities naturally.
"Good" compared to what? How you evaluate that one is better than the
other in this case? Obviosuly, you wouldn't be able to use the R-fators
as the criteria. I guess I know how, but I'm not aware that anyone has
ever done it (another little project for someone enthusiastic).
Overall, I conclude quoting one of my favorite papers:
"The choice of reﬁnement against F**2 or F has generated more
discussions than it probably warrants. (...)"
"Structure refinement: some background theory and
J. Appl. Cryst. (2008). 41, 491–522
All the best!
More information about the phenixbb