[QE-users] scf convergency depends on the number of mpi processes !!!

[Mahmoud Payami Shabestari]

Dear Takahiro,



Thank you for sharing your experience.

As far as I know, the self-consistent values of total energy and 
magnetization depends on how the spin-up and spin-dn electrons accommodate 
the KS levels. That is, it depends on the value of specified "nbnd". If 
choosing the number of processors affect those values, it may somehow, in a 
mysterious way affects the number of KS states?!.

One practical workaround seems to be:

-For a given scf input, add the number of processors to other parameters 
(such as ecutwfc, ecutrho, k-mesh, smearing (mv, mp, . . .), nbnd and so 
forth. In other words, obtain the parameters for each chosen "np-value" in 
mpirun.

Please correct me if I am too much out.



Bests,

Mahmoud 







Hi Mahmoud,

Could you upload your input that can reproduce the issue? If you are
not able to do so, could you make a smaller input that reproduces your
issue?

Actually, I am curious about it because I had a similar issue[1] and
postponed the research. By looking into the things in common, we may
be able to find the root cause of our trouble.

[1] My question on a similar issue
https://www.mail-archive.com/users@lists.quantum-espresso.org/msg42591.html

Sincerely,
Takahiro

---Sender---
Takahiro Chiba
Graduate school of CSE, Hokkaido University, Japan
Group:   https://www.cse.hokudai.ac.jp/en/lab/725/
Mail:      takahiro_chiba at eis.hokudai.ac.jp


On Tue, Nov 29, 2022 at 1:05 AM Mahmoud Payami Shabestari via users
<users at lists.quantum-espresso.org> wrote:
>
> Hi All,
>
> I am experiencing that the success in scf cycle depends on the number of 
processes used in mpirun. That is, for example, for a given scf input when I 
use "mpirun -np 2 pw.x < input.in",
> it gives the converged result in a reasonable number of iteration; but, on 
the other hand, if I instead use "mpirun -np 8 pw.x < input.in", the system 
does not converge numerically.
> First I thought it is somehow a problem of numerical error accumulation. 
So, I used in compilation of QE the FFTW3 as prescribed in the manual. And 
even used "-lfftw3l" (long-double) to cure this problem, but some other 
numerical problems happened in vc-relax job.
>
> I would appreciate if anybody helps to understand the roots of this 
dependency and how to control it.
>
> Bests,
> Mahmoud Payami
> NSTRI, AEOI, Tehran, Iran
>
> Email: mpayami at aeoi.org.ir
> Phone: +98 (0)21 82066504
> --------------------------------------------------------
>
> _______________________________________________
> The Quantum ESPRESSO community stands by the Ukrainian
> people and expresses its concerns about the devastating
> effects that the Russian military offensive has on their
> country and on the free and peaceful scientific, cultural,
> and economic cooperation amongst peoples
> _______________________________________________
> Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
> users mailing list users at lists.quantum-espresso.org
> https://lists.quantum-espresso.org/mailman/listinfo/users
_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (www.max-centre.eu)
users mailing list users at lists.quantum-espresso.org
https://lists.quantum-espresso.org/mailman/listinfo/users
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20221128/95f9ceb9/attachment.html>