[CP2K-user] [CP2K:21130] Re: Counterpoise correction with Grimme D4

[Holger Sassnick]

Hi Quentin,

Thank you for the help and the swift response. You are right, the 
dispersion interaction of "ghost" atoms is (wrongly) added which leads to 
these unreasonable values. As far as I understand, I can just manually sum 
up the energy contributions of the fragments, replacing  the dispersion 
interaction energy with the one from the fragment without ghost atoms. 
Taking those total energy and calculating the interaction energy and 
BSSE-corrected total energy leads then to values similar to PBE or PBE-D3.

I think it would be also great if the implementation in CP2K could take 
care of ghost atoms and calculate all the fragment energies correctly as is 
done for the Grimme-D3 and other van der Waals corrections.

Have a great start to the week.
All the best,
Holger 

Quentin Pessemesse schrieb am Sonntag, 9. Februar 2025 um 01:54:45 UTC+1:

> Also, the order of magnitude of your "BSSE-corrected" interaction energy 
> looks like the order of magnitude of E(disp)AB, which would make sense if 
> the ghost atoms are not treated as ghost by the empirical dispersion 
> correction
>
> Le dimanche 9 février 2025 à 01:39:46 UTC+1, Quentin Pessemesse a écrit :
>
>> Hi Holger, 
>> Counterpoise correction is a correction to the electronic energy, you 
>> should reason only on the electronic energies. The dispersion energy of the 
>> isolated fragments has no physical meaning, and the D3/D4 empirical 
>> correctoin plays no part in the BSSE as it is added after the SCF, and only 
>> depends on the geometry.
>> Here, I think CP2k is giving dispersion correction to the ghost atoms, 
>> calculating both the error that comes from basis functions of fragment 
>> being used to build the density of fragment B (BSSE), and adding some 
>> dispersion energy of the fragments and total system as well.
>> Instead of :
>> BSSE = (EA − EA(B)) + (EB − E (A)B)
>> You get:
>> ([E(elec)A + E(disp)A] - [E(elec)A(B) - E(disp)AB]) + ([E(elec)B + 
>> E(disp)B] - [E(elec)(A)B - E(disp)AB]) = BSSE + (E(disp)A + E(disp)B - 
>> 2*E(disp)AB)
>> Try to run the BSSE single point calculation without the empirical 
>> dispersion and substract it from the interaction energy you get with D3/D3 
>> correction. If it does not fix the issue, maybe I'm mistaken and something 
>> else is wrong.
>> Hope this helped :)
>> Q.
>> Le samedi 8 février 2025 à 13:36:41 UTC+1, Holger Sassnick a écrit :
>>
>>> Hello,
>>>
>>> lately I have been trying to calculate the adsorption energy of water in 
>>> the CAU-23 MOF with different XC functionals. To avoid the quite 
>>> significant BSSE of CP2K's MOLOPT basis sets, I had to apply a counterpoise 
>>> correction.
>>>
>>> However, when using the Grimme D4 method the obtained values didn't 
>>> really make sense as they resulted in a positive interaction energy (I have 
>>> attached the corresponding input and output files). The  same calculation 
>>> with the PBE functional or PBE + Grimme D3 gives a negative interaction 
>>> energy (the absolute value is also significantly smaller).
>>>
>>> I was wondering whether this is a bug in the code? Would it be possible 
>>> that the ghost atoms are not properly treated by the interface to the DFTD4 
>>> library?
>>>
>>> I would be very grateful for some feedback.
>>>
>>> Thanks in advance and all the best,
>>> Holger 
>>>
>>

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