<div dir="ltr"><div dir="ltr"><div>I am not sure that the calculation of stress is implemented with meta-GGA.</div><div><br></div><div>SCAN behaves better than other meta-GGA, but still it is numerically unstable. See for instance here: <a href="https://gitlab.com/QEF/q-e/issues/32">https://gitlab.com/QEF/q-e/issues/32</a>. Before trying difficult calculations with SCAN you should verify whether you can do simple ones.</div><div><br></div><div>Paolo</div><div><br></div></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Apr 20, 2019 at 3:33 AM Giovani Rech <<a href="mailto:gio.pi.rech@gmail.com">gio.pi.rech@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif;font-size:small">Hello all,</div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif;font-size:small">Have anyone tried structure optimization using rvv10-scan?</div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div><div class="gmail_default" style="font-family:"trebuchet ms",sans-serif;font-size:small">I'm trying to optimize a structure (graphite) at 0.0 kbar taking into account van der Waals interactions. For such, I'm using the SCAN+rVV10 by setting "input_dft = 'rvv10-scan'". What I'm getting as a result makes no sense, with unreasonable pressures. Here's a plot of the pressure and volume as a function of optimization step:</div><div class="gmail_default"><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><div><img src="cid:ii_juot3kiq2" alt="image.png" width="562" height="213"><br></div></div><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div><div style="font-family:"trebuchet ms",sans-serif;font-size:small">When I got this values I was using version 6.4.0 and then tried again with 6.3 and finally with the latest version, 6.4.1, and got the same values (plotted above). Here's the input that I used:</div><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div></div></div><blockquote style="margin:0px 0px 0px 40px;border:medium none;padding:0px"><div><div class="gmail_default"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><font face="monospace, monospace">&CONTROL<br></font><font face="monospace, monospace"> title = "graphite_rvv10_vcrelax" ,<br></font><font face="monospace, monospace"> calculation = 'vc-relax' ,<br></font><font face="monospace, monospace"> restart_mode = "from_scratch" ,<br></font><font face="monospace, monospace"> outdir = "./" ,<br></font><font face="monospace, monospace"> pseudo_dir = "/home/giovani/graphite/pseudo" ,<br></font><font face="monospace, monospace"> prefix = "gC" ,<br></font><font face="monospace, monospace"> disk_io = 'default' ,<br></font><font face="monospace, monospace"> verbosity = 'default' ,<br></font><font face="monospace, monospace"> etot_conv_thr = 1.0D-4 ,<br></font><font face="monospace, monospace"> forc_conv_thr = 1.0D-3 ,<br></font><font face="monospace, monospace"> nstep = 400 ,<br></font><font face="monospace, monospace"> tstress = .true. ,<br></font><font face="monospace, monospace"> tprnfor = .true. ,<br></font><font face="monospace, monospace"> /<br></font><font face="monospace, monospace"> &SYSTEM<br></font><font face="monospace, monospace"> A = 2.47000e+00 ,<br></font><font face="monospace, monospace"> C = 8.68000e+00 ,<br></font><font face="monospace, monospace"> nat = 4,<br></font><font face="monospace, monospace"> ntyp = 1,<br></font><font face="monospace, monospace"> ecutwfc = 80 ,<br></font><font face="monospace, monospace"> ecutrho = 320 ,<br></font><font face="monospace, monospace"> input_dft = 'rvv10-scan' ,<br></font><font face="monospace, monospace"> ibrav = 4 ,<br></font><font face="monospace, monospace"> /<br></font><font face="monospace, monospace"> &ELECTRONS<br></font><font face="monospace, monospace"> electron_maxstep = 200,<br></font><font face="monospace, monospace"> conv_thr = 1.00000e-06 ,<br></font><font face="monospace, monospace"> startingpot = "atomic" ,<br></font><font face="monospace, monospace"> startingwfc = 'atomic' ,<br></font><font face="monospace, monospace"> mixing_mode = "plain" ,<br></font><font face="monospace, monospace"> mixing_beta = 7.00000e-01 ,<br></font><font face="monospace, monospace"> mixing_ndim = 8,<br></font><font face="monospace, monospace"> diagonalization = 'david' ,<br></font><font face="monospace, monospace"> diago_thr_init = 1e-4 ,<br></font><font face="monospace, monospace"> /<br></font><font face="monospace, monospace"> &IONS<br></font><font face="monospace, monospace"> ion_dynamics = 'bfgs' ,<br></font><font face="monospace, monospace"> ion_positions = 'from_input' ,<br></font><font face="monospace, monospace"> upscale = 100 ,<br></font><font face="monospace, monospace"> trust_radius_max = 1.0D-3 ,<br></font><font face="monospace, monospace"> /<br></font><font face="monospace, monospace"> &CELL<br></font><font face="monospace, monospace"> cell_dynamics = 'bfgs' ,<br></font><font face="monospace, monospace"> press = 0.0 ,<br></font><font face="monospace, monospace"> press_conv_thr = 0.05 ,<br></font><font face="monospace, monospace"> cell_factor = 1.2 ,<br></font><font face="monospace, monospace"> /<br></font><font face="monospace, monospace">ATOMIC_SPECIES<br></font><font face="monospace, monospace"> C 12.0107 C.SR.ONCVPSP.PBEsol.stringent.upf <br></font><font face="monospace, monospace">ATOMIC_POSITIONS crystal<br></font><font face="monospace, monospace">C 0.0000000000 0.0000000000 0.000000000 <br></font><font face="monospace, monospace">C 1/3 2/3 0.000000000 <br></font><font face="monospace, monospace">C 1/3 2/3 1/2 <br></font><font face="monospace, monospace">C 2/3 1/3 1/2 <br></font><font face="monospace, monospace">K_POINTS automatic <br></font><font face="monospace, monospace"> 6 6 2 0 0 0 </font></blockquote></div></div></blockquote><div dir="ltr"><div class="gmail_default"><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div><div style="font-family:"trebuchet ms",sans-serif;font-size:small">I then tried the same optimization using PBE, by just commenting the 'input_dft' line, and got values of both pressure and volume converging to fairly reasonable values (as plotted below) which makes me think that the problem might be with the rVV10-scan option. Have anyone else had this kind of problem? Any ideas on how this could be fixed?</div><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><div><img src="cid:ii_juot233k1" alt="image.png" width="562" height="216"><br></div><div><br></div><div>Also, when testing and comparing the results of both approaches with verbosity=high to investigate which contribution to the pressure was wack, I noticed that almost all the pressure matrices were more or less similar, except for 'exc-cor stress', that was of the same order of magnitude but opposite signs, and 'core-core stress', which was off both in magnitude and in sign. I'm not sure if this is relevant to the problem, but I thought it could help in finding a solution.</div><div><br></div><div>Thank you for your attention,</div><div>Best regards,</div><div>Giovani Rech</div><div><br></div><div>Universidade de Caxias do Sul,</div><div>Caxias do Sul - RS, Brazil</div></div><div style="font-family:"trebuchet ms",sans-serif;font-size:small"><br></div></div></div></div>
_______________________________________________<br>
Quantum Espresso is supported by MaX (<a href="http://www.max-centre.eu/quantum-espresso" rel="noreferrer" target="_blank">www.max-centre.eu/quantum-espresso</a>)<br>
users mailing list <a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a><br>
<a href="https://lists.quantum-espresso.org/mailman/listinfo/users" rel="noreferrer" target="_blank">https://lists.quantum-espresso.org/mailman/listinfo/users</a></blockquote></div><br clear="all"><br>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div>Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,<br>Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>Phone +39-0432-558216, fax +39-0432-558222<br><br></div></div></div></div></div>