[Wien] The new method of optimizing the internal parameter

[karima Physique]

Dear Prof. Laurence Marks
Thank you very much for your answer
*For the case of my calculations, I want to optimize the internal
parameters of an atom of a **chalcopyrite**, **usually I used MSR1a without
-min (old WIEN2k versions) :*
*runsp -fc 1*
*save xxx*
*i change MSR1 to MSR1a *
*runsp -fc 0.5 -ec 0.00001 -cc 0.001 *
*is this method better than -min option? or it's the opposite*



Le lun. 15 oct. 2018 à 16:31, Laurence Marks <L-marks at northwestern.edu> a
écrit :

> There is in my opinion no "right" method. The question is what are you
> trying to do?
>
> Case 1: A structure with fixed positions or a problem where you "don't
> care" about minor forces, e.g. calculating a simple bulk structure. Then
> just "runsp -cc 0.0001 -ec 0.0001" is fine. (I prefer to use -cc as well as
> the default -ec).
>
> Case 2: A simple structure where there might be minor forces that you do
> care about. Then something like "runsp -cc 0.0001 -ec 0.0001 -fc 1" first
> and check the forces. Iff they are too large for you, then "save -f -d
> PreMin ; runsp -cc 0.001 -ec 0.0001 -min" or similar.
>
> Case 3: A more complex structure where you know the positions are not
> quite right. I suggest using something like
> runsp -cc 0.01 -ec 0.1 -fc 4
> save -f -d PreMin
> runsp -cc 0.001 -ec 0.0001 -fc 1 -min
>
> This avoids converging too much at first when you know the result won't be
> right until the internal minimization has been done. In addition, MSR1a
> often works better when started from a partial minimization where the
> density and pseudo-charges are somewhat converged. For a large problem add
> "-noHinv", I have had problems with -min and -it in the past.
>
> On Mon, Oct 15, 2018 at 9:03 AM karima Physique <physique.karima at gmail.com>
> wrote:
>
>> Dear Wien2k user;
>>
>> According to user guide, after a SCF cycle with runsp -fc 1 we continue
>> with  run runsp -min
>> I want to know which of these two methods is the correct one:
>> 1)
>> runsp -fc 1
>> runsp -min
>> runsp -min -fc 0.5 -ec 0.0001 -cc 0.001
>>
>> or
>> 2)
>> runsp -fc 1
>> runsp -min -fc 0.5 -ec 0.0001 -cc 0.001
>>
>
>
> --
> Professor Laurence Marks
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought", Albert Szent-Gyorgi
> www.numis.northwestern.edu ; Corrosion in 4D:
> MURI4D.numis.northwestern.edu
> Partner of the CFW 100% program for gender equity, www.cfw.org/100-percent
> Co-Editor, Acta Cryst A
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