<div dir="ltr"><div>Dear Fabio,</div><div>you are right, I forgot to switch to the f03 version the call to the mgga functional routine.</div><div>I do not guarantee anything about the results, but now you can properly set the c parameter of TB09 as I told in the previous email. At line 24 I have put zero as default value for c, but with no particular reason.</div><div>I don't know how old is you version of QE, but this file has been taken and modified from the latest version in the develop branch.</div><div>Hope it helps,<br></div><div>Fabrizio<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Nov 8, 2019 at 5:44 PM Fabio Costa <<a href="mailto:fabiocosta4@hotmail.com">fabiocosta4@hotmail.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">
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Dear Fabrizio</div>
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Thank you for your quick reply</div>
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I followed your advice, and now I'm obtaining strange results. I'm running some tests with silicon, and to begin with, the scf run with mBJ reports a negative gap. In the pw.x output, the highest occupied level is higher in energy than the lowest unoccupied
level, resulting on a "gap" of -0.972 eV. Just to compare, the same calculation done with PBE results on an expected result of ~0.8 eV gap. Going further, I plotted the density of states for both cases, and for my surprise, the result obtained with mBJ has
no gap at all, as can be seen from the attached file.</div>
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Also, I'm not sure if I proceeded in the right way, but I tried to change the value of the parameter "c" by changing it at line 24 from xc_mgga_drivers.f90, and recompiling pw.x . After doing this, the result was exactly the same, so my guess is that maybe
I misunderstood how to change it.</div>
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Sorry for the trouble, and thank you for your patience</div>
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Fábio Costa</div>
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<div id="gmail-m_-5412385069165581995divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>De:</b> users <<a href="mailto:users-bounces@lists.quantum-espresso.org" target="_blank">users-bounces@lists.quantum-espresso.org</a>> em nome de Fabrizio Ferrari <<a href="mailto:ferrariruffino.fz@gmail.com" target="_blank">ferrariruffino.fz@gmail.com</a>><br>
<b>Enviado:</b> sexta-feira, 8 de novembro de 2019 11:51<br>
<b>Para:</b> Quantum ESPRESSO users Forum <<a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a>><br>
<b>Assunto:</b> Re: [QE-users] On the use of the modified Becke-Johnson (TB09) functional</font>
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<div>Dear Fabio,</div>
<div>I added some lines in the attached file 'Modules/xc_mgga_drivers.f90' so that, by replacing it with the original one, you should be able to set the c parameter in tb09. You can do it directly into that module by setting the initial value of cc_param or
in any part of the program by calling the routine 'set_cc_for_tb09(xx)' (but in case you may need to adjust the module dependencies).</div>
<div>Before the compilation you need to add the '-lxcf03' in LD_LIBS in the make.inc file</div>
<div>Hope it helps,</div>
<div>Fabrizio<br>
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<div dir="ltr">On Wed, Nov 6, 2019 at 8:36 PM Fabio Costa <<a href="mailto:fabiocosta4@hotmail.com" target="_blank">fabiocosta4@hotmail.com</a>> wrote:<br>
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Dear users and developers</div>
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After some more attempts to use the TB09 functional, I ended up finding this previous post: <a href="https://lists.quantum-espresso.org/pipermail/users/2019-April/042619.html" id="gmail-m_-5412385069165581995x_gmail-m_-1846458044245260968LPlnk619023" target="_blank">https://lists.quantum-espresso.org/pipermail/users/2019-April/042619.html</a> ,
and after changing v_of_rho.f90, the code is now able to end without any error.</div>
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In my attempts, I'm performing the calculations as an initial scf run with a PBE pseudopotencial, and then another scf run, now with restart_mode = 'restart' and input_dft = 'MGGA_X_TB09'. By following this procedure, as described in E. Germaneau's paper, the
calculations do converge.</div>
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The issue now is that the gap energies I'm finding are very large. For example, for silicon, the calculations result in a 2.8 eV gap, larger even than the results presented in the paper, where the values ranged between 1.9 to 2.3. Despite the large gaps, the
band structure and DOS agree well with the ones obtained with PBE.</div>
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Is there any way to improve these results. My first guess is to adjust the "c" parameter in the mBJ functional. After some searching through the routines and Libxc files, I'm still clueless on how to proceed on this matter.</div>
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Any further suggestions will be much appreciated</div>
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Thank you</div>
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Fábio Costa</div>
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<div id="gmail-m_-5412385069165581995x_gmail-m_-1846458044245260968appendonsend"></div>
<hr style="display:inline-block;width:98%">
<div id="gmail-m_-5412385069165581995x_gmail-m_-1846458044245260968divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" face="Calibri, sans-serif" color="#000000"><b>De:</b> users <<a href="mailto:users-bounces@lists.quantum-espresso.org" target="_blank">users-bounces@lists.quantum-espresso.org</a>>
em nome de Fabio Costa <<a href="mailto:fabiocosta4@hotmail.com" target="_blank">fabiocosta4@hotmail.com</a>><br>
<b>Enviado:</b> segunda-feira, 14 de outubro de 2019 13:10<br>
<b>Para:</b> <a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a> <<a href="mailto:users@lists.quantum-espresso.org" target="_blank">users@lists.quantum-espresso.org</a>><br>
<b>Assunto:</b> [QE-users] On the use of the modified Becke-Johnson (TB09) functional</font>
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Dear all</div>
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I'm having some difficulties to work with the TB09 functional. After some reading, I found in some old posts that this can be done by compiling QE with Libxc, and by adding the line 'input_dft='tb09'' in the pw.x input.</div>
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When I try to use this functional, the scf calculation always ends like this:</div>
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total energy = NaN Ry Harris-Foulkes estimate = -11.24358313 Ry estimated scf accuracy < 0.01858366 Ry iteration # 18 ecut= 120.00 Ry beta= 0.10 Davidson diagonalization with overlap %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Error in routine cdiaghg (7): eigenvectors failed to converge %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<br>
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<span style="color:rgb(0,0,0);font-family:Calibri,Helvetica,sans-serif;font-size:12pt">What draws my attention is that always in the last cycle before the error the total energy is printed as NaN. The parameters to the calculation seem to be fine, as it ends
smoothly without the input_dft line.</span><br>
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<div><font size="3" face="Calibri, Helvetica, sans-serif" color="#000000">By searching in the QE user guide, there is a reference to the work of E. Germaneau, which lead me to his paper
<font face="Calibri, Helvetica, sans-serif" color="#000000"><font size="3"><span style="font-size:12pt;line-height:normal">(</span></font></font><span style="margin:0px;font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(136,136,136);text-align:left;display:inline;line-height:normal">DOI:</span><span style="margin:0px;font-family:Roboto,Arial,sans-serif;font-size:12px;color:rgb(136,136,136);text-align:left;display:inline"><span style="margin:0px;font-family:Calibri,Helvetica,sans-serif;font-size:12pt;line-height:normal"> </span></span><span style="margin:0px;font-family:Calibri,Helvetica,sans-serif;font-size:12px;outline:currentcolor none medium;background-image:none;text-align:left;display:inline"><a href="http://dx.doi.org/10.1016/j.cpc.2013.02.020" rel="noopener" style="margin:0px;font-family:Roboto,Arial,sans-serif;outline:currentcolor none medium;background-image:none;display:inline" target="_blank"><span style="font-size:12pt;line-height:normal">10.1016/j.cpc.2013.02.020</span></a></span><span style="margin:0px;font-family:Calibri,Helvetica,sans-serif;font-size:12pt;outline:currentcolor none medium;background-image:none;text-align:left;display:inline;line-height:normal">)</span>,
where the results of his implementation are presented. Even </font><font face="Calibri, Helvetica, sans-serif" color="#000000"><span>though, it is unclear to me how to use the functional </span></font><font face="Calibri, Helvetica, sans-serif" color="#000000">correctly.<font size="3"> </font></font></div>
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<div><font size="3" face="Calibri, Helvetica, sans-serif" color="#000000"><span>Thanks for any assistance</span></font></div>
<div><font size="3" face="Calibri, Helvetica, sans-serif" color="#000000"><span>Fábio Costa</span></font></div>
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