DFTB3 D3(BJ) GAMMA

[Dobromir A Kalchevski]

Hello valued developers and users,

I am trying to setup DFTB3 with D3 correction and GAMMA damping and I can't find the answers to all of my questions in the forum threads. Also some answers are not completely clear to me.

1) If I am to use the D3 correction - is it enough to include 

          DISPERSION_TYPE D3(BJ)
          DISPERSION_PARAMETER_FILE ${LIBPATH}/dftd3.dat

or should I also include the &VDW_POTENTIAL section and where if I am not using DFT (&XC section)

2) does D3(BJ) work with DFTB3 or does only D3 work

3) are both the D3 and the D3(BJ) parameters in the dft3d.dat file. If not - for D3(BJ) I can find only a1, a2 and s8, but I can't find anywhere the fourth one. Why are the default values set to 0

4) is the keyword DFTB3_PARAM in KIND the Hubbard parameter and is it necessary. The 3ob .skf files technically include it, basically does CP2K read it from the .skfs.

5) is using 3ob enough for DFTB3 or do I have to include the keyword DIAGONAL_DFTB3 in &DFTB

6) if HB_SR_GAMMA is the GAMMA damping for hydrogen bonds, is its use recommended for general organics at the moment or it would rather worsen the results, as before

I am attaching an example input file for QM/MM Metadynamics.

Best Regards,

Dobromir