[CP2K-user] [CP2K:20391] Re: Different ways to run PBE50?

[Frederick Stein]

Dear Mikhayla,
The first approach is correct. But you can make the second approach running 
by adding the HF section. The LibXC-related sections only affect the DFT 
part, not the HF part. It is always up to you to set it up because 
different systems require different setups regarding EPS_SCHWARZ, 
EPS_SCHWARZ_FORCES, MAX_MEMORY, CUTOFF_RADIUS etc.
HTH,
Frederick

Mikhayla Clothier schrieb am Freitag, 28. Juni 2024 um 18:23:26 UTC+2:

> Hello,
>
> I would like to use the PBE50 functional. I followed the tutorial provided 
> on the website (
> https://www.cp2k.org/exercises:2017_uzh_cp2k-tutorial:hybrid) where the 
> PBE50 functional is created by manually tuning the PBE and HF contributions,
>
>     &XC
>         &XC_FUNCTIONAL
>             &PBE
>                 SCALE_X 0.50
>                 SCALE_C 1.0
>             &END PBE
>         &END XC_FUNCTIONAL
>         &HF
>             FRACTION 0.50
>         &END HF
>     &END XC
>
> However, within the manual, there seems to be a separate way to call the 
> PBE50 functional from the LibXC library by simply saying 
>
>     &XC
>         &XC_FUNCTIONAL
>             &HYB_GGA_XC_PBE50
>             &END HYB_GGA_XC_PBE50
>         &END XC_FUNCTIONAL
>     &END XC
>
> without the need to manually specify the HF contribution. I ran both 
> approaches with a single water molecule to compare, and I got different 
> energies. Also, just using the HYB_GGA_XC_PBE50 approach did not result in 
> the "Hartree Fock exchange energy" being printed in the output.
>
> Which method is the correct approach? If its the first, how does the 
> HYB_GGA_XC_PBE50 functional work?  I am using the 2022.1 version of CP2K 
> with the 4.1.4 version of OpenMPI.
>
> I've attached the output files to this post. The one for manually setting 
> PBE50 is named 
> "water_manual.out" and the one where I just set the functional as 
> HYB_GGA_XC_PBE50 is called "water_hyb.out." If I need to upload my input 
> files as well, please let me know!
>
> Thank you!
>
> Mikhayla Clothier
>

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