[CP2K-user] [CP2K:21482] Re: frequencies

[Frederick Stein]

Dear Sihem,
How much time do you need for a force calculation on the same machine with 
8 processes? Your total runtime will be 6*<number of atoms> in your system 
as the elements of the Hessian will be determined from symmetric finite 
difference quotients of the analytical gradients. Please be aware that a 
vibrational analysis requires a very accurate setup especially with your 
required displacement. Your EPS_SCF is definitely too low for that, your 
CUTOFF and the EPS_DEFAULT in the QS section could be also improved. The 
general recommendation is a value 1.0E-7 to 1.0E-8 for EPS_SCF. You need 
analytical gradients with an accuracy of several digits as too noisy 
gradients will render the frequencies meaningless. The expected differences 
in gradients should be at least one or two orders of magnitude higher than 
the accuracy of the gradients.
Best,
Frederick

Sihem AZIZI schrieb am Montag, 19. Mai 2025 um 20:46:26 UTC+2:

> Dear all,
>
> I've been running a frequency calculation for over a month and it's still 
> running. I don't know what's wrong. Can someone help me?
> Best regards,
> Sihem
>

-- 
You received this message because you are subscribed to the Google Groups "cp2k" group.
To unsubscribe from this group and stop receiving emails from it, send an email to cp2k+unsubscribe at googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/cp2k/adb2a9e9-b612-4c8d-991f-210e786b49d6n%40googlegroups.com.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.cp2k.org/archives/cp2k-user/attachments/20250519/5128f7a9/attachment.htm>