<div dir="ltr"><div>Increase smearing: 0.0005 is very small. Don't use diagonalization='cg' unless you have a good reason to.<br><br></div>Paolo<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Wed, Aug 5, 2015 at 2:42 PM, Yevgen Melikhov <span dir="ltr"><<a href="mailto:melikhovyy@yahoo.com" target="_blank">melikhovyy@yahoo.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div style="color:#000;background-color:#fff;font-family:Helvetica Neue-Light,Helvetica Neue Light,Helvetica Neue,Helvetica,Arial,Lucida Grande,Sans-Serif;font-size:16px"><div>
</div><div><span lang="EN-US">Dear all users of QE,</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">I am trying to relax GaAs doped with a
little bit of Mn and with some point defects and, of course, I have some
problems in doing that.</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">In order to construct my initial structure
I took cubic cell GaAs with 8 atoms and translated it: (I) 3x2x2 to produce a structure
with 96 atoms and (II) 3x3x3 to produce a structure with 216 atoms. After that
I substitute Ga with Mn (where necessary) and introduce point defects (where
necessary). </span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">The structure with 96 atoms (sometimes 94
or 95 depending on the problem) with GAMMA point relaxes quite well (please see
the attached input file). </span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">However, I could not relax the structure
with 216 atoms (sometimes 214 or 215) (please see the attached input and output files). </span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">If I choose GAMMA point only (that is, of
course, what I wanted to speed up calculations), the error is:</span></div>
<div><span lang="EN-US">%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div><span lang="EN-US">Error in routine efermig (1):</span></div>
<div><span lang="EN-US">Internal error, cannot bracket Ef </span></div>
<div><span lang="EN-US">%%%%%%%%%%%%%%%%%%%%%%%</span></div>
<div><span lang="EN-US">which usually happens in the SCF iteration
#2 of the first BFGS cycle.</span></div>
<div><span lang="EN-US">After checking the forum and playing with
the parameters I decided to increase the number of k-point. </span></div>
<div><span lang="EN-US"> </span></div>
<div dir="ltr"><span lang="EN-US">If I choose more k-points (as in the attached
file), the SCF cannot converge (usually this happens within the second or
sometimes third BFGS cycle) for 70-100 cycles and, due to time limit on the
cluster, the job is not finished. I tried to restart the job but the problem,
in my opinion, is not in having not enough time to finish SCF calculations but rather
in oscillations of the scf accuracy (</span><span lang="EN-US"><span lang="EN-US">please see the extracted parts of the output file)</span>. The first BFGS cycle usually is converged
within 10-20 SCF cycles.</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">Is my assumption that I need to <a name="14efde3ebf2864f6_conv_thr"></a><a name="14efde3ebf2864f6_idp269376"></a><span>change
conv_thr</span> to lager values correct: the number of atoms doubled (96 vs
216), so is the energy (-10300 Ry vs -23000 Ry), and therefore, at least I need
to double the conv_thr (currently it is at its default value 1.0D-6)? For such
a big system may I even increase it further 1.0D-4?</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">Thank you in advance for any
hints/comments!</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">Yevgen Melikhov</span></div>
<div><span lang="EN-US"> </span></div>
<div><span lang="EN-US">Lab of X-ray and Electron Microscopy
Research</span></div>
<div><span lang="EN-US">Institute of Physics, PAS</span></div>
<div><span lang="EN-US">Warsaw, Poland</span></div><div dir="ltr">
</div></div></div><br>_______________________________________________<br>
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Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone <a href="tel:%2B39-0432-558216" value="+390432558216" target="_blank">+39-0432-558216</a>, fax <a href="tel:%2B39-0432-558222" value="+390432558222" target="_blank">+39-0432-558222</a></font></span></span></div></div></div></div>
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