<div dir="ltr"><div>Dear Fabio,</div><div>there has been quite recently a 'more consistent' incorporation of libxc functionals into the QE code (look at 'develop' branch in GitLab).</div><div>In order to use them, as you already did, you have to put their names into the input_dft string, but it is necessary to write their complete name, so, for example, in your case it is MGGA_X_TB09, not just TB09 ( a complete list of the names is shown at: <a href="https://www.tddft.org/programs/libxc/functionals/">https://www.tddft.org/programs/libxc/functionals/</a> ).</div><div>However, that functional belongs to a subset of functionals that need additional information with respect to most of the other cases in order to be properly used so, at the moment, there are no guarantees on their correct operation.</div><div><br></div><div>Best regards,</div><div>Fabrizio<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Oct 14, 2019 at 3:11 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">
<div dir="ltr">
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
Dear all</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
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>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
When I try to use this functional, the scf calculation always ends like this:</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
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>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<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>
</div>
<div style="font-family:Calibri,Helvetica,sans-serif;font-size:12pt;color:rgb(0,0,0)">
<br>
</div>
<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:medium none currentcolor;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:medium none currentcolor;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:medium none currentcolor;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>
<div><br>
</div>
<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>
</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>