QuantumATK Forum
QuantumATK => General Questions and Answers => Topic started by: ams_nanolab on September 29, 2016, 13:08
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Is it possible to see the van der waals component of forces between different layers of a stacked structure ?
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Do you mean by using a method such as DFT+D2 or DFT+D3? F_tot = F_DFT + F_vdW, and you want to know how much is _vdW. Is it correct?
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Yes, DFT-D2 for example.
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No, there is no flag to set in ATK that would print out the DFT-D component of the forces. Also, I am not sure those numbers would carry real physical meaning. The DFT-D methods are fitted to the particular GGA functional in use, so the DFT-D component will vary depending on which GGA you are using, e.g. PBE og PBEsol. Thus, the vdW component itself does not contain *all* vdW-like contributions.
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Is it possible to at least plot the nature of the potential between two groups (layers) of atoms in a multi-layered structure?
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I really don't know how much mean it gives, but you could just try to compute the forces with and without dispersion corrections (after optimizing with D2 on, of course).
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What suggested by Anders will give you exactly what you want: E(D2) = E(DFT+D2) - E(DFT). The same is valid for the forces. Of course it will be functional dependent.
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Okay thanks.