I, too, love the smell of cooking (or cooked?) jobs in the morning.

Cheers

Nigel

---
Nigel W. Moriarty
Building 33R0349, Molecular Biophysics and Integrated Bioimaging
Lawrence Berkeley National Laboratory
Berkeley, CA 94720-8235
Email : nwmoria...@lbl.gov
Web  : CCI.LBL.gov
ORCID : orcid.org/0000-0001-8857-9464


On Thu, Jan 18, 2024 at 1:16 PM James Holton <jmhol...@lbl.gov> wrote:

> Hey there Robert,
>
> Refmac has a keyword called "kill" that I think is what you are looking
> for.  It is documented here:
>
> https://www2.mrc-lmb.cam.ac.uk/groups/murshudov/content/refmac/refmac_keywords.html
>
>    You can specify a conditional exit based on R factor, etc. Or you can
> just create a specified file containing "stop Y" from an external
> process.  I use it when running refmac on a cluster that has run time
> limits but difficult-to-predict CPU speeds.
>
> Phenix, I don't think has a checkpointing feature. Not that I know of.
>
> Amber does support checkpointing and now counts as a refinement program
> since support for structure factor restraints was added in 22.
>
> Personally, when I do refinements I do dozens to hundreds of
> macro-macro-cycles. As in, take the pdb file output by one run and feed
> it into another run. There is an instantiation overhead to doing this,
> as you note, but I like my models to be super converged. I define
> convergence as the x,y,z,B and occ values in the pdb file are not
> changed by the refinement program. This does not happen quickly, but it
> does eventually happen. Yes, you can get oscillations, but one way to
> deal with those is to add a bit more damping, or to adjust the x-ray
> weight down and then up and then back to auto again. This "weight snap"
> tends to take things that were dangling from a cliff in the energy
> landscape and knock them to the ground. After that, the oscillations are
> less common.
>
>   And like an equilibrated chromatography column, an xyz-converged model
> is the best way to know that when you edit and re-refine, everything you
> see is due to the edit, and not some other process that just wasn't
> finished yet.
>
> That's what I do. Maybe I just want to feel like I've got something
> cooking while I sleep...
>
> Cheers,
>
> -James Holton
> MAD Scientist
>
> On 1/18/2024 3:04 AM, Robert Oeffner wrote:
> > Hi,
> >
> > I am wondering if authors of refinement programs would like to consider
> putting on their users wish list the ability of refinement programs to
> automatically terminate once the refinement has reached convergence.
> Various refinement metrics such as R factors, CC or RMS values typically
> will reach a plateau once the refinement of a macromolecular structure with
> X-ray or EM-data has converged and further macro-cycles of refinement will
> no longer improve the structure. The default number of macro-cycles in
> programs such as Phenix-refine and Refmac are probably sensible for most
> cases but in some cases it would be nice if the programs automatically
> extended the number of macro-cycles as needed (or decreased the number).
> >
> > The user can of course examine log files from refinement themselves and
> decide whether to continue refinement. But since starting a new session of
> refinement appears to always create an initial fluctuation in the
> refinement metrics before they align with the values of the last
> macro-cycles in the previous refinement session, the user is compelled to
> do at least, say 3 or more macrocycles in addition to whatever may be
> needed for reaching convergence. I guess it would therefore be more
> efficient if this was implemented directly in the refinement programs and
> presented as an option for the user to choose.
> >
> > There could be cases where alternate conformations of a structure will
> repeatedly be oscillating in and out of density thus causing the refinement
> metrics also to oscillate. Hopefully such cases could be covered by gauging
> the level of fluctuations of the refinement metrics and terminate the
> refinement accordingly.
> >
> > Many thanks,
> >
> > Robert
> >
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