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

[Takahiro Chiba]

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
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