[Pw_forum] Applying vdW to only part of a system

[Tone Kokalj]

On Mon, 2017-09-11 at 17:54 +0200, Evren Ataman wrote:
> I think, the only thing you need to do is to set the name for the
> atoms of the benzene as, say C1, and set the C6 parameters for these
> C1 atoms to of C and set the rest of the atoms' C6 parameters to
> zero.

Actually you need to set them to almost-zero (say, 1d-6 or something
similar). If you set them to zero then default C6 value will be used
instead; see the respective code excerpt in Modules/mm_dispersion.f90:

  IF ( in_C6 (ilab) > 0.0_DP ) THEN
     C6_i  ( ilab )  = in_C6 (ilab)
  ELSE
     C6_i  ( ilab )  = vdw_coeffs(1,i)
  END IF

This reveals that custom C6 value (in_C6) will be used only if it is >
0.0, otherwise default will be used (vdw_coeff).

Which C6 values are actually used is printed in the output (check!).

Best regards, Tone Kokalj
-- 
J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia 
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