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<p><font size="-1">Dear Anuja</font></p>
<p><font size="-1">the calculation with a very dense k-point mesh is
most likely looping through the k points and taking a lot of
time before printing out anything. <br>
</font></p>
<p><font size="-1">It is not necessary though to run the scf
calculation with the very fine mesh; it is sufficient to run the
scf calculation with a feaisble k point mesh for which you are
confident to be at convergens, once done the scf calculation
with the feasible converged mesh you may run nscf calculation
with the finer mesh that you need for the epsilon.x
calculation. <br>
</font></p>
<p><font size="-1">To speed up the calculation you may try to use
the k-point parallelism: in suppose that you are using 20 MPI
processes and that 4 of them are sufficient to run the iterative
diagonalization for one k point, you can divide your 20 MPI
processes in 5 pools each diagonalizing and assigned subset of
the total k points. To do this you just have to run your pw.x
command as:</font></p>
<p><font size="-1"><tt>mpirun -np 20 pw.x -nk 5 -i input_nscf >
out_nscf </tt></font><font size="-1"> <br>
</font></p>
<p><font size="-1">I hope this helps. <br>
</font></p>
<p><font size="-1">kind regards - Pietro</font><br>
</p>
<div class="moz-cite-prefix">On 01/07/19 17:44, Anuja Chanana
wrote::<br>
</div>
<blockquote type="cite"
cite="mid:CAAWKNThOfY0RWhZX4dzWWR-5F3EpZ73cCyRBeCPBAB3jaRz7TQ@mail.gmail.com">
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<div dir="ltr">Dear all,
<div>I am trying to run epsilon.x by reading the following
tutorial</div>
<div><a
href="https://www.paradim.org/sites/default/files/2019-05/Band_Structure_and_UV-VIS_Spectra.pdf"
target="_blank" moz-do-not-send="true">https://www.paradim.org/sites/default/files/2019-05/Band_Structure_and_UV-VIS_Spectra.pdf</a> </div>
<div><br>
</div>
<div>The manual says that for the calculation of epsilon, a
finer-k mesh is required like 30x30x30.</div>
<div>I have a triclinic system where </div>
<div>a = 6.3 A b = 6.5 A c = 5.9 A<br>
alpha 121.358 beta 88.3349 gamma 106.391</div>
<div><br>
</div>
<div>If I increase the k-mesh to 30x30x30, the initial scf
simulation doesn't run at all.</div>
<div>Nothing gets written. Why does that happen?</div>
<div>Has anyone experienced it before?</div>
<div><br clear="all">
<div>
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style="background-color:rgb(0,0,0)"></span><span
style="background-color:rgb(255,255,255)">Thanks <br>
</span></font></span>
<div>
<div>Anuja</div>
</div>
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