[CP2K-user] [CP2K:21129] Re: Counterpoise correction with Grimme D4

[Quentin Pessemesse]

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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