[CP2K-user] [CP2K:21486] Re: frequencies

[Frederick Stein]

Dear Sihem,
Without any further information (input and output file), it is hard to give 
any recommendations. Optimize the force calculation by making the 
calculation as accurate as necessary and as 
cheap as possible (CUTOFF, EPS_DEFAULT, EPS_SCF, play around with mixing 
schemes, ...).
Regards,
Frederick

Sihem AZIZI schrieb am Dienstag, 20. Mai 2025 um 11:30:12 UTC+2:

> Dear frederick,
> Thanks a lot for your response.
> I have another question for you. On another machine I ran an optimization 
> calculation for a Ru slab (3 layers) with an H2 molecule. And the 
> calculation has been running for a month. What should I do to make it 
> converge faster?
> Thank you again for your help.
> Sihem
>
> On Monday, May 19, 2025 at 9:05:04 PM UTC+1 Frederick Stein wrote:
>
>> 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
>>>
>>

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