<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div dir="ltr">ph.x currently does not support the three-body terms with the D3 dispersion correction. You can turn it off with the dftd3_threebody tag in pw.x, and follow the three step procedure you outlined in your email. If you want to include the three-body terms, you can use the supercell approach (e.g., phonopy) instead of DFPT with ph.x. <div dir="ltr"><br></div><div dir="ltr">Three-body terms tend to have a pretty small effect in my experience, but that's system-dependent, in principle, and you might want to test it. Refer to the original D3 papers for a discussion. Three-body terms are not used at all in VASP, for reference (but they're hidden in the source code). </div><div dir="ltr"><br></div><div dir="ltr">I also generally recommend using D3 with BJ damping or D3M/D3M-BJ instead of the standard "zero damping" D3. (dftd3_version flag in pw.x). </div><div dir="ltr"><br></div><div dir="ltr">Omar A. Ashour</div><div dir="ltr">UC Berkeley </div><div dir="ltr"><br><blockquote type="cite">On May 14, 2024, at 2:51 PM, Jing Lian Ng <jinglian@utexas.edu> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr"><div dir="ltr">Hello all,<div><br></div><div>I am currently trying to perform phonon calculation with DFT-D3 correction. Based on what I read from d3hess.x documentation, I believe I can include dispersion effects on vibrational frequencies by:</div><div><ol><li>Relax / Scf calculation</li><li>run d3hess.x</li><li>run ph.x</li></ol>However, I encounter an error on step2, with the error message being:</div><div><br></div><div> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br> task # 28<br> from pbcgdisp : error # 1<br> Atom displacement not implemented with the threebody term<br> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br></div><div><div><br></div><div>My input file for scf is as follows:</div><div><br></div><div>##########################################################################</div><div>/<br>&SYSTEM<br> ntyp = 1<br> nat = 2<br> ibrav = 0<br> ecutwfc = 100<br> ecutrho = 400<br> vdw_corr = 'DFT-D3'<br>/<br>&ELECTRONS<br> mixing_mode = 'plain'<br> mixing_beta = 0.3<br>/<br>&IONS<br>/<br>&CELL<br>/<br>ATOMIC_SPECIES<br>H 1.008 H.upf<br></div><div><br></div><span class="gmail_signature_prefix"><div><span class="gmail_signature_prefix">CELL_PARAMETERS angstrom<br>5.21657500000000 0.00000000000000 0.00000000000000<br>0.00000000000000 6.04926000000000 0.00000000000000<br>-6.40884630521040 0.00000000000000 36.38325638013446<br></span></div><div>##########################################################################<br></div><div><br></div><div>Can someone advise on what could be the possible error? Thanks!</div>-- </span><br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr">Best regards,<div><b>Jing Lian Ng</b>, PhD Student</div><div>Wang Material Group</div><div><span style="font-size:14px;font-family:Arial,sans-serif;color:rgb(191,87,0)">The University of Texas at Austin</span><span style="font-size:14px;font-family:Arial,sans-serif"><font color="#333f48"> | </font><a href="http://che.utexas.edu" target="_blank"><font color="#0b5394">McKetta Department of Chemical Engineering</font></a><font color="#333f48"> | </font><a href="https://wangmaterialsgroup.com/" title="https://wangmaterialsgroup.com/" style="margin-top:0px;margin-bottom:0px" target="_blank"><font color="#0b5394">Wang Materials Group</font></a></span><br></div></div></div></div></div>
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