[Wien] Slow convergence of charge

[Shafqat Hussain Shah]

Just to clarify that it took normally around 80 iterations with MSR1a  and
not with single point total energy calculation with MSR1. It converges
normally if I use experimental structure or structures generated by
Optimizer with option 1, 3 and 4. In all these calculations I used MSR1a
for relaxation of internal parameters.
Problem arises when I use the optimized lattice parameters and vol and try
to relax experimental internal parameters.

On 16 December 2014 at 14:08, Laurence Marks <L-marks at northwestern.edu>
wrote:
>
> It is hard to say exactly without repeating the calculation why it is a
> little slow. If it takes 80 cycles for a point calculation with MSR1, 300
> in MSR1a is not a lot.
>
> Often TEMPS converges better than TETRA as it broadens the electronic
> phase changes to second order so the problem is more analytic. I normally
> use 0.0018 room temperature).
>
> ___________________________
> Professor Laurence Marks
> Department of Materials Science and Engineering
> Northwestern University
> www.numis.northwestern.edu
> MURI4D.numis.northwestern.edu
> Co-Editor, Acta Cryst A
> "Research is to see what everybody else has seen, and to think what nobody
> else has thought"
> Albert Szent-Gyorgi
>   Thanks for your response. Even if I do a simple scf calculation with
> MSR1, the charge does not converge with -cc 0.001 for about 200 iterations.
> Anyway I lower the -cc tolerance and give it a try.
>  Meanwhile any other idea/suggestion/comment or problem that has been
> spotted......
>  Some of my input files are attached, if they could help.
>
> On 16 December 2014 at 12:35, Lyudmila Dobysheva <lyuka17 at mail.ru> wrote:
>
>> On 16.12.2014 08:56, Shafqat Hussain Shah wrote:
>>
>>> the atomic positions of the system using MSR1a, it is, unexpectedly,
>>> very slow (around 300 iterations) in charge convergence.
>>> runsp_lapw -p -i 999 -ec 0.0001 -cc 0.001 -fc 0.50
>>> all
>>> the calculations with experimental parameters and Optimizer generated
>>> structures for option 1, 3 and 4 converge nicely (around 80 iterations
>>> with the above mentioned command).
>>>
>>
>> As far as I remember a standard procedure for MSR1a should start from a
>> partly converged solution, that is, first, without MSR1a:
>> run_lapw -p -cc 0.1 -ec 0.25 -fc 20 -i 60
>> save (to clean the directory)
>> then change the case.inm to MSR1a
>> and run_lapw with good criteria for convergence -cc 0.0015
>>
>> I see that in the first iteration you have
>> :DIS=  ( 1.5480230 for atom    3 spin 2)      2.9889210
>> that is rather large. The calculated forces are not correct yet, your
>> system goes far from reality. Maybe for experimental lattice you had
>> started from a converged solution, so forces had been correct in the first
>> iteration already, and finding the equilibrium was short.
>>
>> Best regards
>>   Lyudmila Dobysheva
>> ------------------------------------------------------------------
>> Phys.-Techn. Institute of Ural Br. of Russian Ac. of Sci.
>> 426001 Izhevsk, ul.Kirova 132
>> RUSSIA
>> ------------------------------------------------------------------
>> Tel.:7(3412) 218988(office), 722529(Fax)
>> E-mail: lyu at ftiudm.ru, lyuka17 at mail.ru (office)
>>         lyuka17 at gmail.com (home)
>> Skype:  lyuka17 (home), lyuka18 (office)
>> http://fti.udm.ru/content/view/25/103/lang,english/
>> ------------------------------------------------------------------
>> _______________________________________________
>> Wien mailing list
>> Wien at zeus.theochem.tuwien.ac.at
>> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
>> SEARCH the MAILING-LIST at:  http://www.mail-archive.com/
>> wien at zeus.theochem.tuwien.ac.at/index.html
>>
>
>
> --
> Dr. Shafqat Hussain Shah
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
>

-- 
Dr. Shafqat Hussain Shah
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20141216/a68bf3e3/attachment.html>