[Wien] Slow convergence of charge

[Laurence Marks]

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
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-- 
Dr. Shafqat Hussain Shah
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