[CP2K-user] [CP2K:21380] Re: Struggling to converge single atom calculation

[Frederick Stein]

Dear Harry,
Consider them an inspiration as wB97X-2 is a double-hybrid functional, i.e. 
it has an additional MP2 correlation contribution and requires a rather 
different amount of HF exchange. Read the paper defining wB97X (and 
potentially also wB97X-2) how to set up the parameters.
HTH,
Frederick

Harry Richardson schrieb am Donnerstag, 17. April 2025 um 13:24:50 UTC+2:

> Thank you very much for your response Frederick, 
>
> I see there are some xc_sections that use the omega97X-D functional, 
> Do you think either:
> WB97X_2LP.sec 
> <https://github.com/cp2k/cp2k/blob/master/data/xc_section/WB97X_2LP.sec> 
> or WB97X_2TQZ.sec 
> <https://github.com/cp2k/cp2k/blob/master/data/xc_section/WB97X_2TQZ.sec>
> may be suitable, or would it be better to define it myself. 
>
>
> Thanks again 
> Harry 
> On Thursday, April 17, 2025 at 12:04:05 PM UTC+1 Frederick Stein wrote:
>
>> 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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