[CP2K-user] [CP2K:21819] Mismatch between CP2K computed Force constant (a.u)and Gaussian computed force constant(mDyne/angstrom)

[Beliz Gökmen]

Hi Naina,
Thanks for reporting this. You can find the updated code in the development 
version of cp2k <https://github.com/cp2k/cp2k>.
Best,
Beliz

On Monday, 8 September 2025 at 05:17:23 UTC-5 Naina Sethi wrote:

> Even with periodic none in subsystem gives same results.
>
> On Monday, September 8, 2025 at 2:43:25 PM UTC+5:30 Johann Pototschnig 
> wrote:
>
>> You are still missing the "PERIODIC NONE" in the SUBSYS section:
>>
>> https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/SUBSYS/CELL.html#CP2K_INPUT.FORCE_EVAL.SUBSYS.CELL.PERIODIC
>>
>> There is a warning in your output.
>>
>> On Friday, September 5, 2025 at 8:42:47 PM UTC+2 Naina Sethi wrote:
>>
>>> Dear Prof. Hutter,
>>> Is there any mistake in my input setup? Could you please help.
>>>
>>> On Monday, August 25, 2025 at 3:05:15 PM UTC+5:30 Naina Sethi wrote:
>>>
>>>> I am using CP2K version 2024.3 and attempted to reproduce one of the 
>>>> sample calculations on the benzene molecule (
>>>> https://www.cp2k.org/exercises:2015_ethz_mmm:infra_red). However, I am 
>>>> unable to obtain force constants similar to those that i get from gaussian. 
>>>> While the vibrational frequencies, IR intensities, and reduced masses agree 
>>>> perfectly with Gaussian results, the force constants differ 
>>>> significantly(specifically for lower frequency regime). This discrepancy is 
>>>> concerning because the magnitude of the force constants is critical for my 
>>>> work. Could you please advise whether this might be related to changes in 
>>>> the code since the example was prepared, or if I might be missing something 
>>>> in my setup?
>>>>
>>>> I am attaching the Input and output files from CP2K and gaussian 
>>>> calculation. Kindly suggest. 
>>>>
>>>> Thank you very much for your time and guidance.
>>>>
>>>> Best regards,
>>>>
>>>>

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