[CP2K-user] [CP2K:19956] NON_LOCAL dispersion in ENERGY_CORRECTION ?

[Ralf Frischmann]

Hi JH,

thanks for the quick reply and the clarification. Wasn't 100% sure whether 
my assumption above were actually correct.

Another possible option for getting NL dispersion in these cases could be 
to apply the dispersion NL functional in a post-SCF-type fashion (quantum 
chemistry codes ORCA and psi4 allow this as an option). Then it should be 
possible to take RHO from a converged HFX-SCF procedure and "stuff it" into 
the existing NL energy+gradient routines prior to the DFT response 
calculation, so with that no response calculation should be needed for the 
NL dispersion part. 

Having the post-SCF NL option in general would also be a nice and "fairly 
easy" to do CP2K feature. Relative errors introduced by that are usually 
very small (~0.0x kcal/mol) in gas phase calculations, and substantial 
computational savings might result from it.

Regards,

Ralf



  


On Thursday, February 22, 2024 at 11:12:00 AM UTC+1 Jürg Hutter wrote:

> Hi
>
> thank you for raising this issue. I have opened a new feature request 
> issue on
> github (#3277) and have disabled nl-vdW functionals in EC calculation in 
> the
> current cp2k version.
> The main problem is the required 2nd derivative of the functionals for
> the gradient calculation.
>
> regards
> JH
>
> ________________________________________
> From: cp... at googlegroups.com <cp... at googlegroups.com> on behalf of Ralf 
> Frischmann <ralf.p.f... at gmail.com>
> Sent: Thursday, February 22, 2024 5:57 AM
> To: cp2k
> Subject: [CP2K:19950] NON_LOCAL dispersion in ENERGY_CORRECTION ?
>
> Dear all,
>
> are there plans already to implement a working NON_LOCAL dispersion 
> correction for the &ENERGY_CORRECTION part?
>
> It appears to me that currently only the PAIR_POTENTIAL type delivers a 
> finite Edisp value in the CP2K output file, although input files with a 
> NON_LOCAL &VDW_POTENTIAL specifications get accepted with no further 
> warning from the code, but do return Edisp = 0.d0 in the EC part of the 
> output.
>
> An inspections of the SUBROUTINE ec_disp(qs_env, ec_env, calculate_forces) 
> in the file energy_corrections.F with a hard-wired call to the function 
> calculate_dispersion_pairpot() further supports that assumption.
>
> Thanks in advance for any clarification on that subject!
>
> Regards,
>
> Ralf
>
>
>
>
>
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