[CP2K-user] [CP2K:18228] QS Method, Basis, Potential and settings for organic molecules

DMT dobromirak at gmail.com
Tue Dec 20 13:56:32 UTC 2022


I am interested in organic molecules, which are to be eventually modeled 
over surfaces, in solvents in reactions and also in molecular crystals. I 
am new to the software, so I have questions regarding choice of QS METHOD, 
BASIS_SET, POTENTIALS and some settings. I have found a few input files, 
searched the group (some google) and the manual, but there are quite a few 
things I am not familiar with.

For basis sets I search the cp2k/data directory of the source code and I 
search the Basis Set Exchange web site. 
- are there other ways of finding basis sets +/- potentials ?

So far I am left with the impression that all GTH-POTENTIALs are only 
available optimized for certain DFT functionals and are hence unsuitable 
with other functionals ?
I assume DZVP-GTH basis has a double-zeta valence shell + polarizations ? 
Does it also exist with diffusion functions (let's say I need density a 
little further away - an anion, a complex, etc.) ? How good is it compared 
to TZVP (all-electron) or def2-TZVP ? Or compared to 6-31g* or cc-pVDZ ? 
Which basis sets for CP2K would be like 6-31g*, TZVP, def2-TZVP and cc-pVDZ 
... and why not cc-pVTZ for each of the following QS METHODs: DFTB, GAPW, 

Which CP2K basis sets have diffusion shells ?

!> I cannot deduce the shells of basis sets by reading the basis set files, 
so is there a way to actually see how many s, p, d and/or f shells does a 
CP2K basis set have ? I can guess whether there are polarizations or not 
based on the element and type of shells, but I cannot guess the same for 
diffusion orbitals, as they are of the same type as the covalent shell 

!> What QS METHOD is good for organics and not just for semiconductors or 
metals ? Which are faster and which are slower ? Which BASIS_SET and/or 
POTENTIAL should I use for good / scientific / publication quality 
calculations ?

Can I use one QS METHOD for a central molecule and another QS METHOD and 
BASIS_SET for surrounding solvent molecules, without QM/MM ? Or one qs 
method and basis for a central molecule and another method + basis 
combination for a surface (graphene or semi-conductor or metal) ?

Is it a good idea to calculate molecular crystals with qs method + basis 
different from those for single molecules / complexes.

The way I understand it, plane wave basis sets may not be the best for 
organics ?

!> What type of dispersion is most appropriate for organic molecules / 
organo-metallic complexes, with or without a solvent. And for molecular 
crystals ?

!> I see that there are some new DFT types in CP2K, beyond the kind of DFT 
that Gaussian does. Should I pick any of them and for which kind of systems 

Best Regards,

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