[QE-developers] Incompatible FFT grid in ph.x calculation

[Xiao Zhang]

Dear Paolo,

Thanks for the reply. I attached the output of scf from 6.5 here. I think
they are very similar with only minor differences in some last digits, and
actually the phonon calculation using 6.5 works with both scfs, while 6.6
fails with both.

I realized that in 6.6, an additional line shows: Fft bands division: nmany
= 1 (line 15). Not sure if this means anything or not?

Thanks!
Best!
Xiao

On Fri, Aug 14, 2020 at 8:31 AM Paolo Giannozzi <p.giannozzi at gmail.com>
wrote:

> It would be useful to see the scf output for v.6.5 as well
>
> Paolo
>
> On Fri, Aug 14, 2020 at 9:14 AM Xiao Zhang <xiaozha at umich.edu> wrote:
>
>> Dear QE developers,
>>
>> I'm sending the email asking about an error I get from the phonon
>> calculations in the 6.6 version of quantum espresso. I'm trying to run
>> phonon calculation for 2H SiC and have the scf run finished with no
>> problem, but when I run phonon calculation following that, I received an
>> incompatible FFT grid error. This happened only with the new version of QE
>> while using the exact same input, QE 6.5 works fine and provides output. I
>> was wondering if this is something we expect? (I do realize there is one
>> potentially relevant tag on the release note under "fixed")
>>
>> I attached one example just in case it might help: This is 2H-SiC and I
>> attached the input and output from scf, input and output from ph.x from
>> both 6.5 and 6.6. The k-points and cutoffs are reduced for quick tests, but
>> converged k-points and cutoffs show the same issue. The structure is
>> relaxed within QE, and the PP used is ONCV-PBE. I'm a bit confused why this
>> is seen in phonon calculation but not the scf calculation? I assumed that
>> if it's a problem of my input structure, I should've seen a problem in
>> both? Any hint or suggestions would be very helpful!
>>
>> Thanks a lot!
>> Best!
>> Xiao Zhang
>> Department of Materials Science and Engineering
>> University of Michigan, Ann Arbor
>>
>> _______________________________________________
>> developers mailing list
>> developers at lists.quantum-espresso.org
>> https://lists.quantum-espresso.org/mailman/listinfo/developers
>>
>
>
> --
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
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