[Pw_forum] vdW force in mm_dispersion.f90 and Van der Waals functional

yukihiro_okuno at fujifilm.co.jp yukihiro_okuno at fujifilm.co.jp
Wed Feb 9 02:01:13 CET 2011

Dear PWSCF developers.

I want to evaluate the force from vdW interaction and

compare the DFT-D and vdW functional implemented in PWSCF.

Then, I saw the source code of mm_dispersion.f90, the implementation of

I found in force_london in mm_dispersion Modules,  a condition

IF (ata /= atb) THEN



But,  if ata ==atb ( same atom in the system), there must be  a
contribution of vdW force

from  the periodic images of the same atom (index =ata=atb)  within the
cutoff radius of vdW,

I think the condition (if ata/=atb)  drops such a contribution.

And  in CVS version of PWSCF implementation of  vdW functional in vDW_DF

it seems there is a stress calculation function, but still  no force
calculation function

within non-local vdW functional.  Are there plan to implement the force
from vdW

interaction within SCF scheme.


Yukihiro Okuno.

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