[CP2K-user] [CP2K:21807] Need help with making AIMD simulations faster!

['Akanksha' via cp2k]

Hello Dr. Krack,

Thank you for responding so quickly.
Based on your suggestion, I ran a few benchmarking tests and was able to
identify the issue. I realized my SLURM script was getting overwritten
during submission, which resulted in all of my calculations running on a
single core.

I really appreciate your time and guidance. Thank you.

Regards,
Akanksha



On Fri, Sep 5, 2025 at 5:05 AM Krack, Matthias <matthias.krack at psi.ch>
wrote:

> Hi
>
>
>
> At a first glance your setup looks fine to me. I don’t understand why it
> runs so slow. Maybe, you are overcommitting the available resources which
> often causes a significant slowdown. I suggest to use only one OMP thread
> per MPI rank. Running your input using an increasing number of CPU cores
> shows a reasonable scaling up to 64 CPU cores (cp2k v2025.2):
>
>
>
> *CPU cores* (MPI ranks)
>
> *Average time per MD step [sec]*
>
> 8
>
> 78
>
> 16
>
> 40
>
> 32
>
> 22
>
> 64
>
> 14
>
> 128
>
> 12
>
>
>
> Best
>
>
>
> Matthias
>
>
>
> *From: *'Akanksha' via cp2k <cp2k at googlegroups.com>
> *Date: *Friday, 5 September 2025 at 05:36
> *To: *cp2k <cp2k at googlegroups.com>
> *Subject: *[CP2K:21799] Need help with making AIMD simulations faster!
>
> Hi,
>
>
>
> I am trying to run an AIMD simulation of an explicitly solvated system of
> ~280 atoms at 300 K and 1 bar pressure. However, I have noticed my
> simulation is very slow (Only reached about 200 fs in a day). I do have a
> few motion constraints on my solute molecules, which I believe could also
> make the simulations slower.
> Each MD step takes about 200 seconds to run with 6-10 SCF iterations. I am
> new to CP2K and AIMD in general, so I am not sure if this speed is normal.
> Could anyone please help me figure out if I am missing something or if
> there are any ways to make these simulations faster? Your help will be very
> much appreciated.
>
> Here are the parameters I am using:
> 1) CP2K/2024.2 version (mpirun -np 32 -c 4 cp2k.psmp)
> 2) Anthracene and 2-bromophenol in a DMF box (17*14*14)
> 2) Calculation started from the last snapshot of a 5 ns classical MD run.
> 2) PBE-D3(BJ)/DZVP-MOLOPT/GTH
> 3) ASPC(3) extrapolation
> 4) DIIS as the OT minimizer with FULL_SINGLE_INVERSE preconditioner
>
> 5) Timestep: 0.5 fs
> 5) CSVR thermostat with 50 fs time constant.
>
> I have also attached the full input file and a plot of the
> constant-of-motion wrt time for your reference.
>
> Please let me know if you need more information from me. I would really
> appreciate any feedback you can provide.
>
> Thank you,
>
> Akanksha
>
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