[CP2K-user] [CP2K:22428] Re: Large time difference between NEB images

[Frederick Stein]

Dear Sofia,
I am not familiar with NEB-calculations but it may help if you could post 
an output file/the output files of a calculation that actually finished (to 
have the CP2K timing report at the very end) to help us investigating your 
bottleneck.
Best,
Frederick

Sofia Scozziero schrieb am Dienstag, 15. September 2026 um 23:32:16 UTC+2:

> Hi everyone, 
>
> I've recently started working with CP2K and I'm running into the following 
> issue. When doing NEB calculations some images take significantly more time 
> per OT step than others, I'm not talking about number of SCF steps to 
> converge but wall time per OT step, which is up to 15x slower for some of 
> the images (tipically I've found issues with maybe 2-3 images out of 12 per 
> run). Now a 2x-3x difference is manageable but when it gets past the 5x its 
> problematic. This has been happening running in a cluster on 3-4 nodes of 
> 64 cpus each, and I'm running purely on MPI with this
>
> mpirun -np $SLURM_NTASKS --bind-to core cp2k.psmp -i neb.inp -o neb.out
>
> and open mp threads set explicitly to 1.
>
> I've brought this up to my system admins and they haven't been able to 
> detect any issues like over subscription, load balancing or any of the 
> common culprits. I'm clueless on what could be happening. On the physics 
> side everything seems ok... I'm not getting any unreasonable energies or 
> gaps, the total charge and spin also seem ok.
>
> I'm attaching my input (.inp file) and a shortened txt file with the lines 
> I'm more concerned about. I tested the convergence parameters vs a plane 
> wave calculation and with successive cp2k calculations so I believe they 
> should be Ok.
>
> Extra note: I've tried on 1 and 2 nodes with a smaller system and this 
> problem didn't come up, granted being a different system it is not the same 
> problem.
>
> Any help is welcome, and thanks in advance,
>
> Sofía
>

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