[CP2K-user] [CP2K:21377] Re: Struggling to converge single atom calculation

[Frederick Stein]

Dear Harry,
You have to setup a suitable HF section (see 
https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XC/HF.html). CP2K 
will not do it by itself except of an available shortcut as stated in the 
manual (see 
https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/DFT/XC/XC_FUNCTIONAL.html). 
Compare the already available xc_sections in the CP2K data directory 
(https://github.com/cp2k/cp2k/tree/master/data/xc_section) for their setup.
Best,
Frederick

Harry Richardson schrieb am Donnerstag, 17. April 2025 um 11:15:16 UTC+2:

> i have been suggested to use multiplicity 3, I have tried and does not 
> affect convergence, please see attached. 
>
> On Thursday, April 17, 2025 at 9:36:10 AM UTC+1 Harry Richardson wrote:
>
>> Hi all, I am pretty new to DFT and trying to run some single atom (C) DFT 
>> to use as a subtraction when fine tuning a machine learned force field for 
>> MD. As such it needs to be run at the same level of theory as my full 
>> system calculations. 
>>
>> I just need single point energies. 
>>
>> At the moment it is not converging, I have attached my input and output 
>> files, i am using the omega97X-D functional. 
>>
>> Some thing I have tried include: 
>>
>>    - Changing the box from periodic to non periodic
>>    - Reducing mixing
>>    - Increasing & decreasing the size of the box 
>>    - Changing multiplicity 
>>    - Reducing cutoff 
>>    
>> The energy change per step seems to reduce over steps but does not 
>> converge. 
>>
>> I am using the DZVP-MOLOPT basis set and GTH-PBE-q4 potential as 
>> suggested in here: https://www.cp2k.org/exercises:2018_uzh_cmest:faq 
>> potentially that is the issue? 
>>
>> Would appreciate any help you can provide 
>>
>> Thanks
>>
>

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