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#1 | van der Waals correction in relaxation datum

Thu Dec 02, 2021 3:06 pm (Last edited: Thu Dec 02, 2021 3:07 pm)

Hi everyone,

Using the release version of Fleur, I performed a relaxation of bilayer graphene, the relaxed interlayer spacing is ~3.1Å, which may be underestimated. I failed to find the information of van der Waals correction in the user guide, thus I'd like to ask how to use vdW correction in Fleur. If it is not implemented yet, I am considering the binding energy test by varying interlayer spacing. Any discussion would be appreciated, thanks in advance!

Jiaqi

Jiaqi ZHOU
Postdoc
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Modelling Division (MODL)
Institute of Condensed Matter and Nanosciences (IMCN)
Université Catholique de Louvain (UCLouvain)
Chemin des étoiles, 8 - 1348 Louvain-la-Neuve - Belgium

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#2 | RE: van der Waals correction in relaxation datum

Fri Dec 03, 2021 11:46 am

Dear Jiaqi,

there exists a module implementing the approch by Guillermo Román-Pérez and José M. Soler(Phys. Rev. Lett. 103, 096102) into FLEUR. As far as I remember its status is the following:
- Its in the source code (fleur_VDW.F90) but currently not called. So this module would have to be included (probably somewhere in the potential setup) again to be usable. I currently do not know anyone in our team with spare time to do this, but of course you are very welcome to look at it. If you plan to do so and need additional help, please open a corresponding gitlab issue.
- It can be used to calculate a vdW contribution to the total energy and hence your idea of varying the spacing could be feasible.
- It also can be used to calculate a contribution to the potential which could be included in the SCF cycle. However, I would believe that it should also lead to additional force contributions if used in a relaxation that are not implemented.

Hope this helps
Daniel

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#3 | RE: van der Waals correction in relaxation datum

Fri Dec 03, 2021 12:20 pm

Dear Daniel,

Thank you very much for your help, I've found the vdW.F90 file. Thanks for the discussion on the vdW contribution, I will carefully consider all your suggestions.

Regards,
Jiaqi

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