For relaxation of transition metal dichalcogenides (e.g.: WS2) using the VASP code, what is the best choice for vdW correction method (e.g.: DFT-D2, DFT-D3 or optB88-vdW) that can give you good results ?
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2$\begingroup$ This might be helpful $\endgroup$– Thomas ♦Jul 28, 2020 at 15:16
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1$\begingroup$ Also related (in addition to the one Thomas linked): mattermodeling.stackexchange.com/q/63/5 $\endgroup$– Nike DattaniJul 28, 2020 at 18:30
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DFT-D2 is simple and reliable. I've used DFT-D2 for most of my worked on 2D materials but I do I have to caution you that I have not specifically work on TMGs. You can test out the results you obtain from both DFT-D2 and DFT-D3 and compare them. Another idea is to look at literature. There is a labyrinth of data on TMGs and you can look under the 'methods' section of the papers.
This also depends on the kind of functional you use in KS-DFT. If you're using LDA, it's not practical to use vdw corrections because LDA already over-binds and using a vdw correction makes it only worse. If you're using PBE for example, it should be fine.
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$\begingroup$ I'll tack on a couple of relevant papers here: "Are we van der Waals ready", "van der Waals density functional made accurate". $\endgroup$ Jul 29, 2020 at 4:50