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Dear Dr. Kawamura thanks a lot for the patch.
<p><br>
</p>
<p>Dear Giuseppe, <br>
</p>
<p>after discussion of our collaborators with Paolo Giannozzi and Stefano De Gironcoli,
<br>
</p>
<p>we learned that it is possible in QE v 6.1 to use tetrahedra for relax and vc-relax calculations for insulators/semiconductors,</p>
<p>especially using the the optimized tetrahedron method (occupations='tetrahedra_opt'), as reported in the</p>
<p>pw.x manual for version 6.1:</p>
<p></p>
<blockquote>
<pre style="margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> Available options are:
</span></pre>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'smearing'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">gaussian smearing for metals;
see variables </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#smearing"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">smearing</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> and </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#degauss"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">degauss</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">
</span></pre>
</dd></dl>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'tetrahedra'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">Tetrahedron method, Bloechl's version:
P.E. Bloechl, </span><a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.49.16223"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">PRB 49, 16223 (1994)</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">
Requires uniform grid of k-points, to be
automatically generated (see card </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#K_POINTS"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">K_POINTS</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">).
Well suited for calculation of DOS,
less so (because not variational) for
force/optimization/dynamics calculations.
</span></pre>
</dd></dl>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'tetrahedra_lin'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">Original linear tetrahedron method.
To be used only as a reference;
the optimized tetrahedron method is more efficient.
</span></pre>
</dd></dl>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'tetrahedra_opt'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">Optimized tetrahedron method:
see M. Kawamura, </span><a href="https://journals.aps.org/prb/abstract/10.1103/PhysRevB.89.094515"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">PRB 89, 094515 (2014)</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">.
Can be used for phonon calculations as well.
</span></pre>
</dd></dl>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'fixed'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">for insulators with a gap
</span></pre>
</dd></dl>
<span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"></span>
<dl style="margin-left: 1.5em;"><dt><tt><span class="flag" style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">'from_input'</span><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> :</span></tt></dt><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">The occupation are read from input file,
card </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#OCCUPATIONS"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">OCCUPATIONS</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">. Option valid only for a
single k-point, requires </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#nbnd"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">nbnd</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;"> to be set
in input. Occupations should be consistent
with the value of </span><a href="http://www.quantum-espresso.org/wp-content/uploads/Doc/INPUT_PW.html#tot_charge"><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">tot_charge</span></a><span style="font-family: Calibri,Helvetica,sans-serif; font-size: 12pt;">.</span></pre>
</dd></dl>
<p><br>
</p>
<p><br>
</p>
<p>Best,</p>
<p>Chiara<br>
</p>
<dl style="margin-left: 1.5em;"><dd>
<pre style="margin-top: 0em; margin-bottom: -1em;"> </pre>
</dd></dl>
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<div id="x_divRplyFwdMsg" dir="ltr"><font style="font-size:11pt" color="#000000" face="Calibri, sans-serif"><b>De :</b> pw_forum-bounces@pwscf.org <pw_forum-bounces@pwscf.org> de la part de Giuseppe Mattioli <giuseppe.mattioli@ism.cnr.it><br>
<b>Envoyé :</b> mercredi 18 octobre 2017 10:48:15<br>
<b>À :</b> pw_forum@pwscf.org<br>
<b>Objet :</b> Re: [Pw_forum] tetrahedra and vc-relax</font>
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Dear Chiara<br>
You should not use occupations='tetrahedra' for relax or vc-relax <br>
calculations! The reason is clearly stated in the pw.x manual. Use <br>
smearing instead<br>
<br>
<br>
Variable: occupations<br>
<br>
Type: CHARACTER<br>
Description:<br>
Available options are:<br>
<br>
'smearing' :<br>
gaussian smearing for metals;<br>
see variables "smearing" and "degauss"<br>
<br>
'tetrahedra' :<br>
especially suited for calculation of DOS<br>
(see P.E. Bloechl, PRB 49, 16223 (1994)).<br>
Requires uniform grid of k-points,<br>
automatically generated (see below).<br>
Not suitable (because not variational) for<br>
force/optimization/dynamics calculations.<br>
<br>
'fixed' :<br>
for insulators with a gap<br>
<br>
'from_input' :<br>
The occupation are read from input file,<br>
card "OCCUPATIONS". Option valid only for a<br>
single k-point, requires "nbnd" to be set<br>
in input. Occupations should be consistent<br>
with the value of "tot_charge".<br>
<br>
<br>
HTH<br>
Giuseppe<br>
<br>
Quoting chiara.ricca@dcb.unibe.ch:<br>
<br>
> Dear all,<br>
><br>
> I'm trying to perform a "vc-relax" calculation using the tetrahedron <br>
> method with QE v 6.1.<br>
><br>
> The calculation stops after having printed the final geometry, <br>
> during the final scf step.<br>
><br>
> It does not write any error and the scheduler only reports a <br>
> segmentation fault.<br>
><br>
> I have tried with both tetrahedra and tetrahedra_opt, but I have the <br>
> same issue.<br>
><br>
> The problem is not there if I do a "relax" calculation.<br>
><br>
> Please find attached, the input and output of an example.<br>
><br>
> Thanks in advance!<br>
><br>
> Regards,<br>
><br>
> Chiara Ricca<br>
><br>
> ---<br>
><br>
> Postdoctoral fellow<br>
><br>
> University of Bern<br>
<br>
<br>
<br>
GIUSEPPE MATTIOLI<br>
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA<br>
Via Salaria Km 29,300 - C.P. 10<br>
I-00015 - Monterotondo Scalo (RM)<br>
Mob (*preferred*) +39 373 7305625<br>
Tel + 39 06 90672342 - Fax +39 06 90672316<br>
E-mail: <giuseppe.mattioli@ism.cnr.it><br>
<br>
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