[CP2K-user] [CP2K:21387] Re: Struggling to converge single atom calculation

[Harry Richardson]

After checking some other forum posts of people using the same functional i 
believe it should be:

    SCALE_COULOMB 0.22036
    SCALE_LONGRANGE 0.77964

Thanks again 

On Thursday, April 17, 2025 at 3:14:30 PM UTC+1 Harry Richardson wrote:

> Hi Frederick, 
>
> Thank you so much for your support. I read the wb97X-D paper and came up 
> with the following settings for HF.    
>
>     &HF
>     FRACTION 0.22                ! From wB97X-D paper
>     &SCREENING
>       EPS_SCHWARZ 1.0E-10      ! affects convergence / accuracy? (choose 
> same as WB97X_2LP.sec)
>     &END SCREENING
>     &INTERACTION_POTENTIAL
>       POTENTIAL_TYPE TRUNCATED
>       CUTOFF_RADIUS 10.0           ! (didn't see mentioned in paper choose 
> same as WB97X_2LP.sec)
>       OMEGA 0.2                ! From wB97X-D paper
>     &END INTERACTION_POTENTIAL
>   &END HF
>
> With these settings the calculation has converged, the only thing i am not 
> sure about is if I need to scale the coulomb and longrange as is done 
> within WB97X_2TQZ.sec, do I need to use a mixed interaction potential? 
>
>           SCALE_COULOMB 0.678792
>           SCALE_LONGRANGE 0.321208
>
> the paper mentions:
> "one first defines long-range LR and short-range SR operators to partition 
> the Coulomb operator"
>
>  but i couldn't see exact values listed anywhere?
>
> Thanks again for all your help, I owe you a beer!
>
> On Thursday, April 17, 2025 at 12:42:02 PM UTC+1 Frederick Stein wrote:
>
>> 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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