[CP2K-user] [CP2K:21170] Re: Counterpoise correction with Grimme D4

[Jürg Hutter]

Hi

the MOLOPT basis sets are optimized to perform for a wide range of
systems (molecules, solutes, solids, open structures), while keeping a
small number of functions for performance reasons.
BSSE is of similar size as for comparable size Gaussian basis sets.
For MD calclulation we tested and confirm that BSSE is typically
a constant shift on energies and does not affect dynamics.
If you want to have smaller/no BSSE you have to increase the
number of functions and e.g. include the atomic ground
state functions in the Basis (as in FHI-AIMS). There is the danger
that these near complete basis sets will perform poorly in dense
systems due to bad condition numbers.

regards
JH

________________________________________
From: cp2k at googlegroups.com <cp2k at googlegroups.com> on behalf of Holger Sassnick <holger.sassnick at gmail.com>
Sent: Thursday, February 13, 2025 11:14 AM
To: cp2k
Subject: Re: [CP2K:21142] Re: Counterpoise correction with Grimme D4

Hi Prof Hutter,

thank you for transferring the issue to the github repository. I was also wondering whether it would be reasonable and feasible to design a larger MOLOPT basis set with negligible BSSE. In this context I am also thinking about the training of MLPs, e.g. in this publication (https://pubs.acs.org/doi/10.1021/jacs.4c15287) trajectories were re-calculated with VASP for the training to ensure accurate results.

Fox example, in FHI-Aims the "tight" basis set parameters have hardly any BSSE. I know that the code uses a different localized basis set, so maybe this kind of accuracy cannot be reached with GTOs? I would be happy to hear your opinion on this matter.

All the best,
Holger


Jürg Hutter schrieb am Montag, 10. Februar 2025 um 09:39:16 UTC+1:
Hi

thank you for bringing this to our attention. I have opened a bug report
on the CP2K github page.
https://github.com/cp2k/cp2k/issues
[CP2K:21126] Counterpoise correction with Grimme D4

regards
JH

________________________________________
From: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Holger Sassnick <holger.... at gmail.com>
Sent: Monday, February 10, 2025 7:19 AM
To: cp2k
Subject: [CP2K:21130] Re: Counterpoise correction with Grimme D4

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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