[Pw_forum] Applying vdW to only part of a system

[Alberto Otero de la Roza]

Hi Ian,

It is possible with dispersion corrections based on the asymptotic
formula (like XDM or D2, as described by Evren). Why would you want to
do that, though?  In general, dispersion improves the description of
metals and ionic solids and, one would guess, surfaces. There was a
recent paper by Perdew and Ruzsinszky on the topic, if memory
serves. And I also know for a fact that, for instance, B86bPBE-XDM
reproduces alkali halide and alkaline earth oxide cubic cell lengths
with errors of 0.1 angstrom of less once vibrational effects are taken
into account.

Best,

Alberto

--
Dr. Alberto Otero de la Roza
Department of Chemistry, 
University of British Columbia, Okanagan
Kelowna, British Columbia, Canada V1V 1V7

* Ian Shuttleworth <shuttleworth.ian at gmail.com> [2017-09-11 16:33:30 +0100]:
> Is it possible to apply vdW forces to only a part of system?
> 
> I am thinking of examples where, for example, a vdW adlayer (e.g. benzene)
> sits on a surface, and surface doesn't need vdW corrections.
> 
> If I add the vdw_corr toggle (or if I set an appropriate value
> to 'input_dft') I've understood that vdW are applied to the entire system -
> if this is right, how could I make this option more selective?
> 
> With thanks
> 
> Ian

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