[QE-users] My slab system does not converge during optimization.Can you help me?

[Thomas Brumme]

Dear Jayfe,

having a closer look at your input I'm a bit confused about some things 
but lets try to stick first to your specific
problem - you mentioned in your first email, that the calculation is 
running with elements other than Mn and
that you thus think that Mn is the problem.

Now, did you try replacing the pseudopotential?

Looking at the graph of the SSSP: 
https://www.materialscloud.org/discover/sssp/plot/precision/Mn
I see that the pseudopotential you're using might have some problem - 
even with a dual of 16 it is not really
looking good until a cutoff of about 120 Ry. Sure, phonons and related 
properties are different from standard
scf convergence, but it is weird. Maybe try using the older 0.3.1 
version of the pslibrary.

Did you try to increase the cutoff?

Considering the very same graph of the SSSP, I think that a cutoff of 45 
Ry is just not enough for Mn.
Try increasing in reasonable steps (i.e., 50, 60, 70) with a dual of 8 
or 16 for the 0.3.1 or the 1.0.0 version of
the pslibrary, respectively. If it converges (only one scf, no 
relaxation, but printing the forces) compare results
to see what might be a converged value. How big is the change in the 
total energy? How do the forces
converge? What about magnetization? And so on and so forth... The 
standard way to get a reasonable set of
ecutwfc and ecutrho for your system...

So, concerning your input:

I know that you created the input with some tool, but it does not make 
sense. You should check this...
First of all, delete everything which you don't use, just to be sure 
that there is no problem. Why do you set
esm parameters, if you don't use the method? Why is eamp still set to a 
finite value? Before trying some
different diagonalization methods try the standard 'david'. startingpot 
and startingwfc usually don't need to
be set.

In summary, I would try to change the pseudo and increase the cutoff. 
And I would clean the input. Then you
need to make convergence checks.

Regards

Thomas


On 4/20/21 4:55 PM, Jayfe Anthony Abrea wrote:
>
> Hello Dr. Thomas,
>
> First of all, I would like to thank you for giving your inputs on my 
> case last week. I do hope you can still extend a helping hand on this 
> predicament of mine.
>
> I would like to give you an update on my predicament on optimization 
> process. Attached in this email is my input file in which the eamp was 
> set to zero. During calculations, the results are still oscillating 
> for each iteration. I didn’t stopped the calculation but I can see 
> that it’s not going better. It even gave a positive value for 
> calculated scf energy per iteration as seen in this pic:
>
> https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Eat1rLSbCO9Mth7ra0er6PwBfrWsXtUj9s7f_mOPkckzgA?e=lQWb4L 
> <https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Eat1rLSbCO9Mth7ra0er6PwBfrWsXtUj9s7f_mOPkckzgA?e=lQWb4L>
>
> The accuracies for each iteration are very low for each iteration as 
> seen in this pic:
>
> https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Ebnkk0mfJjlKiFkMffu63HkBYml45BOtNl3q8JjB_JkTJQ?e=ZRpyqc 
> <https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Ebnkk0mfJjlKiFkMffu63HkBYml45BOtNl3q8JjB_JkTJQ?e=ZRpyqc>
>
> Then let me share to you the ongoing result for the magnetization for 
> each iteration in this pic:
>
> https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Eat1rLSbCO9Mth7ra0er6PwBrm1Ki8UqakTaleeJ8Nleng?e=4oIMv9 
> <https://cviscpshs-my.sharepoint.com/:i:/g/personal/jaabrea_cvisc_pshs_edu_ph/Eat1rLSbCO9Mth7ra0er6PwBrm1Ki8UqakTaleeJ8Nleng?e=4oIMv9>
>
> I hope you can shed light to this matter Dr. Thomas. I’m not sure now 
> as to why the Mn cannot undergo proper optimization unlike the Fe and Co.
>
> Best regards,
>
> Jayfe
>
> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for 
> Windows 10
>
-- 
Dr. rer. nat. Thomas Brumme
Theoretical chemistry
TU Dresden - BAR / II49
Helmholtzstr. 18
01069 Dresden

Tel:  +49 (0)351 463 40844

email: thomas.brumme at tu-dresden.de

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