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<span style="">Hi Mohammad, </span></p>
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<span style="">Yes you are right <span style="color:black; border:none windowtext 1.0pt; padding:0cm; background:white"> 'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d' all mean the same thing in Quantum ESPRESSO and refer to the D2 dispersion-correction by Grimme
(2006; <b><u><a href="https://doi.org/10.1002/jcc.20495">https://doi.org/10.1002/jcc.20495</a></u></b>), which computes a on-the-top two-body dispersion energy. As far as I know, the original DFT - D (or to be more precise DFT - D1) method (Grimme, 2004 <b><u><a href="https://doi.org/10.1002/jcc.20078">https://doi.org/10.1002/jcc.20078</a></u></b>)
was limited in its application to a small number of elements, and is not used anymore in modern DFT codes (as a user I know it for Quantum ESPRESSO and CASTEP). Therefore, if authors refer to DFT + D they often mean the DFT + D2 method but please check in
the references of the papers you mentioned (i.e., Grimme 2006 --> DFT + D2; DFT + D --> Grimme 2004). </span> </span></p>
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<span style="color:black; border:none windowtext 1.0pt; padding:0cm; background:white">Regarding your second question: Many so called semiclassical dispersion corrections such as D2, D3, TS and MBD are implemented in Quantum ESPRESSO. An alternative approach
are the so called non-local functionals such as vdw-DF1, vdw-DF2 and rVV-10. Grimme 2016 (<a href="https://doi.org/10.1021/acs.chemrev.5b00533" title="DOI URL"><span style="">https://doi.org/10.1021/acs.chemrev.5b00533</span></a>) has written an excellent
review article about all of these approaches. I know that it is often very hard to decide for the 'right' approach, especially since you don't have any experimental data for comparison. There are loads of benchmarking studies on the various dispersion corrections,
so I would suggest that you choose a correction method that works well for the type of materials you are studying.</span><span style=""> </span></p>
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<span style=""> </span></p>
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<span style="color:black; border:none windowtext 1.0pt; padding:0cm; background:white">HTH,</span><span style=""> </span></p>
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<span style="color:black; border:none windowtext 1.0pt; padding:0cm; background:white">Johannes</span><span style=""> </span></p>
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<span style="">__________________________________________________________________________ </span></p>
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<span style=""> </span></p>
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<span style="">Johannes Meusburger </span></p>
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<span style="">ISIS Neutron and Muon Source, UK </span></p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> users <users-bounces@lists.quantum-espresso.org> on behalf of mohammad maymoun <maymoun17755@gmail.com><br>
<b>Sent:</b> Saturday, February 19, 2022 9:42 AM<br>
<b>To:</b> users@lists.quantum-espresso.org <users@lists.quantum-espresso.org><br>
<b>Subject:</b> [QE-users] The difference between DFT-D and DFT-D2 in QE package</font>
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<div>I am working on decorating 2D materials (carbon based) with halogen atoms. I have readed several papers on decorating 2D materials which include van der Waals correction, some of these papers used DFT-D and others used DFT-D2. But when I looked into the
QE package I found that 'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d' means the same thing.<br>
I am wondering if this is correct or there is a misunderstanding of mine.</div>
<div>Please correct me if I am wrong.</div>
<div>I also have another question: there are several van der Waals corrections available in the QE package including semi empirical and functional. In the absence of experimental data it is difficult to select the compatible van der Waals correction for our
material. Because these methods give different formation energy, cell parameters, band gap,.....</div>
<div>could you please give me advice in this regard.</div>
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<div>--<br>
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<div><span style="font-family:tahoma,sans-serif"><i><font size="2">Best regards,</font></i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i><font size="2"><br>
</font></i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i><font size="2">Mohammad Maymoun</font></i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i><font size="2">******************************</font></i></span></div>
<div>
<div><span style="font-family:tahoma,sans-serif"><font size="2"><i>PhD Student<br>
</i></font></span></div>
<div><span style="font-family:tahoma,sans-serif"><i>Laboratoire des sciences des Matériaux, des Milieux et de la Modélisation (LS3M)</i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i>Faculté Polydisciplinaire de Khouribga<br>
</i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i><font size="2">Université Sultan Moulay Slimane<br>
</font></i></span></div>
<div><span style="font-family:tahoma,sans-serif"><i><font size="2">Béni Mellal , Maroc</font></i></span></div>
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