QS Method, Basis, Potential and settings for organic molecules

[DMT]

Hello,

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, GAPW_XC, GPW, LRIGPW, RIGPW, XTB.

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 orbitals.

!> 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,

Dobromir

[DMT]

Hello,

I kind of did a lot of digging and came up with the following general inputs for PBE and PBE0 for organic, non-periodic systmes.

What do you think ?

Can I optimize them further ?

I guess the system is too small (Li near cyclohexadiene, 14 atoms) to properly test the cutoff in

                &INTERACTION_POTENTIAL
                    POTENTIAL_TYPE TRUNCATED    !TRUNCATED 1/r (Coulomb) POTENTIAL FOR SPEED UP
                    CUTOFF_RADIUS 6.0            !SHOULD BE < HALF THE CELL
                    T_C_G_DATA /home/lsd/cp2k_data/t_c_g.dat     !DATA FOR THE EVAL OF TRUNCATED GAMMA FUNC
                &END INTERACTION_POTENTIAL

and

                !&PBE_HOLE_T_C_LR
                !    CUTOFF_RADIUS 6.0
                !    SCALE_X 0.25
                !&END PBE_HOLE_T_C_LR

but quite frankly even on a larger and periodic system (graphene) there seems to be no speed up.

The EPS_SCHWARZ is set to 1.0E-6 either way.

Best Regards,

Dobromir