[CP2K-user] [CP2K:9301] XC_HYB_MGGA_XC_WB97M_V functional in libxc

[Frederick Stein]

Hi,

I am familiar with the related wB97X-functionals by Head-Gordon, 
unfortunately not with those containing VV10 dispersion corrections like 
wB97(M)-V. Your XC_FUNCTIONAL section is correct.
Use the following INTERACTION_POTENTIAL section
        &INTERACTION_POTENTIAL
          # Chose it a bit less than half the shortest nearest-neighbour 
distance (i.e. cubic box with a=4 A, cutoff = 1.99 A; or cp2k starts 
complaining)
          CUTOFF_RADIUS 4.0
          # c_sr V_sr + V_lr = c_sr V_Coul+(1-c_sr) V_lr
          SCALE_LONGRANGE 0.833 
          SCALE_COULOMB 0.167  # Affects the scaling of the truncated 
potential for periodic systems
          # For non-periodic systems use MIX_CL instead
          POTENTIAL_TYPE MIX_CL_TRUNC
          T_C_G_DATA t_c_g.dat
        &END INTERACTION_POTENTIAL
Finally, you miss the VDW-section to include the VV10 correction (See *https://groups.google.com/forum/#!searchin/cp2k/wb97x%7Csort:date/cp2k/JEvnnfAEgPY/oryDShPd_w0J 
<https://groups.google.com/forum/#!searchin/cp2k/wb97x%7Csort:date/cp2k/JEvnnfAEgPY/oryDShPd_w0J>*). 
They used something like this
      &vdW_POTENTIAL
         DISPERSION_FUNCTIONAL NON_LOCAL
         &NON_LOCAL
           TYPE RVV10
           PARAMETERS 6.3 0.0093
           VERBOSE_OUTPUT
           KERNEL_FILE_NAME /path/to/your/VV10/table/rVV10_kernel_table.dat
           CUTOFF  150
         &END NON_LOCAL
      &END vdW_POTENTIAL
To my knowledge, cp2k provides only parameters for the rVV10 model, not for 
the VV10 model. You should test wether the rVV10 parameters are suitable. 
You might have a further look at the discussions to the wB97X-V functional 
in this forum. (
https://groups.google.com/forum/#!searchin/cp2k/wb97x%7Csort:date/cp2k/JEvnnfAEgPY/oryDShPd_w0J
, 
https://groups.google.com/forum/#!searchin/cp2k/wb97x|sort:date/cp2k/VsG6j38wdwI/rsJYd0ZpBwAJ
, 
https://groups.google.com/forum/#!searchin/cp2k/wb97x|sort:date/cp2k/le-ojRVXWa0/acojYhQ0AwAJ
)
There are also some examples to test wB97X-V. According to the paper where 
wB97M-V was published, you might try some of the databases or the 
dissociation curve of this functional (benzene-argon-dimer) depending on 
what you can afford. When I tested some functionals, dissociation curves 
can be a good choice because the shape differs between different 
functionals as well as optimal distances and bonding energies.
I think Juerg wrote in one of the mentioned threads that you should test 
the different parts (DFT, HF, VV10) of the functional seperately. Because 
there are different flavours of that functional (B97, wB97X, wB97X-V, these 
functionals with different dispersion corrections), there should not be a 
problem to find reference data.

regards

Frederick
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