[GSAS-II] non-negative constraint of occupancy

[Toby, Brian H.]

Sure, limits as part of structure solution but not part of structure refinement. However, if you set a fixed value, you reduce the search space even further and this should not impair solution (except perhaps with neutrons and ambiguity between positive and negative scatters, but how often does one try to solve a truly unknown structure with neutrons?)

> On Nov 20, 2019, at 2:54 AM, Jonathan WRIGHT via GSAS-II <gsas-ii at aps.anl.gov> wrote:
> 
> Hi Brian
> 
> Aren't hard limits useful during structure "solution"? They might reduce the size of search space and increase the radius of convergence.
> 
> Cheers,
> 
> Jon
> 
>> In any case, a constraint would serve to hide that something is wrong with your result. A restraint would make it harder to do that, but still is not addressing the problem.
>> Brian
>>> On Nov 19, 2019, at 10:17 AM, Hao Liu via GSAS-II <gsas-ii at aps.anl.gov <mailto:gsas-ii at aps.anl.gov>> wrote:
>>> 
>>> Hi,
>>> 
>>> Is there a way to constrain the atomic occupancy to be non-negative?
>>> 
>>> Thanks,
>>> Hao
>>> -- 
>>> Hao Liu, Ph.D.
>>> Assistant Professor
>>> Chemistry Department, Binghamton University
>>> 4400 Vestal Parkway East, NY 13902
>>> Tel: +1 (607) 777-4671
>>> Group website <http://chemiris.chem.binghamton.edu/LIU/liu.html>
>>> _______________________________________________
>>> GSAS-II mailing list
>>> GSAS-II at aps.anl.gov <mailto:GSAS-II at aps.anl.gov>
>>> https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii
>> _______________________________________________
>> GSAS-II mailing list
>> GSAS-II at aps.anl.gov
>> https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii
> _______________________________________________
> GSAS-II mailing list
> GSAS-II at aps.anl.gov
> https://mailman.aps.anl.gov/mailman/listinfo/gsas-ii