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<p>Thanks a lot for the fast answer,</p>
<p>as you say, after this warning is printed another step is
performed, and the message:</p>
<p>bfgs converged in  4 scf cycles and  3 bfgs steps<br>
    (criteria: energy < 1.0E-06 Ry, force < 1.0E-15
Ry/Bohr)<br>
</p>
<p>is printed after the last step. The keyword 'converged' is of
course misleading in such a case.<br>
<br>
Should others encounter the same problem, I switched to</p>
<p>&IONS<br>
   ion_dynamics = 'damp'<br>
/<br>
</p>
<p>from the default 'bfgs'. This makes it possible to reduce the
force components to 1.0D-7.<br>
<br>
</p>
<p>Leonid<br>
</p>
<br>
<div class="moz-cite-prefix">On 09/20/2017 02:03 PM, Paolo Giannozzi
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAPMgbCtnUjgA8CEK6gHCwsXtZHz-GQgjW+ZfpJYWkV=Loq5stw@mail.gmail.com">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<div dir="ltr">If you look carefully in the output, you will
notice this:<br>
<div>
<pre class="gmail-m_-3724084907207510950gmail-aLF-aPX-K0-aPE">WARNING: bfgs curvature condition failed, Theta= 0.815
Message from routine bfgs:
history already reset at previous step: stopping
<span style="font-family:arial,helvetica,sans-serif">
</span><span style="font-family:arial,helvetica,sans-serif"><font size="1"><span style="font-family:arial,helvetica,sans-serif"><font size="1">This kind of problem arises when one is very close to convergence and forces
contain too much numerical noise for the minimization to be effective.
Not sure why it performs a further step.
</font></span></font></span></pre>
<pre class="gmail-m_-3724084907207510950gmail-aLF-aPX-K0-aPE"><span style="font-family:arial,helvetica,sans-serif"><font size="1"><span style="font-family:arial,helvetica,sans-serif"><font size="1">Paolo
</font></span></font></span></pre>
<pre class="gmail-m_-3724084907207510950gmail-aLF-aPX-K0-aPE"><span style="font-family:arial,helvetica,sans-serif"><font size="1"><span style="font-family:arial,helvetica,sans-serif"><font size="1">
</font></span></font></span></pre>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Wed, Sep 20, 2017 at 9:56 AM, Leonid
Kahle <span dir="ltr"><<a
href="mailto:leonid.kahle@epfl.ch" target="_blank"
moz-do-not-send="true">leonid.kahle@epfl.ch</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p>Dear all,</p>
<p>A relaxation of a rather large system (Li21 Si3 P3 S24)
is shown as converged even though the force convergence
threshold is not reached. I will paste the final output
below, and the full input and output are attached. I put
a very low threshold 1D-15 to prove my point here, but
also more sensible thresholds are ignored.</p>
<p>As explained in the documentation, but also in this
forum ( <a
class="m_8221411463729769083moz-txt-link-freetext"
href="http://qe-forge.org/pipermail/pw_forum/2004-November/076156.html"
target="_blank" moz-do-not-send="true">http://qe-forge.org/pipermail/<wbr>pw_forum/2004-November/076156.<wbr>html</a>
) convergence of the relaxation is achieved when all the
components of the force vector are smaller than
forc_conv_thr (and energy criterion is met as well). In
the example below this is obviously not the case, but
bfgs is shown as converged without any warning.<br>
</p>
<p>Can anyone help me find an explanation for this? I am
using the parallel version of QE 6.1 compiled with intel
compilers on an x86_64 architecture. <br>
</p>
<p>Many thanks in advance,</p>
<p>Â Â Â Leonid Kahle</p>
<p><span class="m_8221411463729769083moz-txt-tag">-- </span><br>
</p>
<p><font size="-1">Doctoral Assistant <br>
EPFL STI IMX THEOS <br>
ME-D2 1019 (Bâtiment ME) <br>
Station 9 <br>
CH-1015 Lausanne (Switzerland) </font></p>
<p><br>
</p>
<p>Â Â Â Â Forces acting on atoms (cartesian axes, Ry/au):<br>
<br>
    atom   1 type 1  force =    0.00000940  Â
0.00000005Â Â Â 0.00000759<br>
    atom   2 type 1  force =    0.00003922 Â
-0.00005066Â Â -0.00003891<br>
    atom   3 type 1  force =   -0.00000527 Â
-0.00001786Â Â -0.00000047<br>
    atom   4 type 1  force =    0.00000695 Â
-0.00000525Â Â -0.00000490<br>
    atom   5 type 1  force =    0.00000837  Â
0.00000136Â Â Â 0.00000695<br>
    atom   6 type 1  force =   -0.00000139  Â
0.00000800Â Â -0.00000768<br>
    atom   7 type 1  force =   -0.00000042 Â
-0.00000074Â Â -0.00000888<br>
    atom   8 type 1  force =   -0.00002354 Â
-0.00001155Â Â -0.00003861<br>
    atom   9 type 1  force =    0.00001305 Â
-0.00001546Â Â Â 0.00000555<br>
    atom  10 type 1  force =   -0.00001756  Â
0.00002269Â Â -0.00001184<br>
    atom  11 type 1  force =   -0.00000255 Â
-0.00001734Â Â Â 0.00001741<br>
    atom  12 type 1  force =    0.00001174  Â
0.00001759Â Â -0.00001735<br>
    atom  13 type 1  force =   -0.00000633 Â
-0.00000979Â Â Â 0.00000484<br>
    atom  14 type 1  force =   -0.00001325  Â
0.00001294Â Â -0.00000493<br>
    atom  15 type 1  force =    0.00000782 Â
-0.00002956Â Â -0.00000586<br>
    atom  16 type 1  force =   -0.00000317  Â
0.00001363Â Â Â 0.00000878<br>
    atom  17 type 1  force =   -0.00002203  Â
0.00000270Â Â -0.00000480<br>
    atom  18 type 1  force =   -0.00000998  Â
0.00000531Â Â Â 0.00001788<br>
    atom  19 type 1  force =    0.00000060 Â
-0.00000321Â Â -0.00001756<br>
    atom  20 type 1  force =   -0.00000688  Â
0.00002017Â Â Â 0.00000404<br>
    atom  21 type 1  force =   -0.00000129 Â
-0.00000416Â Â -0.00001532<br>
    atom  22 type 2  force =   -0.00000319 Â
-0.00000167Â Â Â 0.00000395<br>
    atom  23 type 2  force =    0.00001103  Â
0.00001040Â Â Â 0.00000626<br>
    atom  24 type 2  force =    0.00000396 Â
-0.00000186Â Â Â 0.00000201<br>
    atom  25 type 3  force =   -0.00001044  Â
0.00000478Â Â -0.00000086<br>
    atom  26 type 3  force =   -0.00001291  Â
0.00000415Â Â -0.00000411<br>
    atom  27 type 3  force =    0.00001756 Â
-0.00000296Â Â Â 0.00000913<br>
    atom  28 type 4  force =   -0.00001578  Â
0.00000879Â Â Â 0.00000423<br>
    atom  29 type 4  force =   -0.00001227  Â
0.00000946Â Â -0.00000839<br>
    atom  30 type 4  force =    0.00001416  Â
0.00001301Â Â Â 0.00001436<br>
    atom  31 type 4  force =    0.00001660 Â
-0.00000202Â Â Â 0.00000659<br>
    atom  32 type 4  force =    0.00003452 Â
-0.00001067Â Â Â 0.00001793<br>
    atom  33 type 4  force =    0.00000938 Â
-0.00001056Â Â Â 0.00000237<br>
    atom  34 type 4  force =   -0.00001496 Â
-0.00000472Â Â Â 0.00000305<br>
    atom  35 type 4  force =   -0.00001625 Â
-0.00000739Â Â -0.00000918<br>
    atom  36 type 4  force =    0.00001063  Â
0.00001606Â Â -0.00000310<br>
    atom  37 type 4  force =   -0.00000110  Â
0.00000394Â Â -0.00000268<br>
    atom  38 type 4  force =   -0.00000163  Â
0.00000039Â Â Â 0.00000700<br>
    atom  39 type 4  force =   -0.00000066 Â
-0.00000016Â Â Â 0.00000132<br>
    atom  40 type 4  force =   -0.00000813  Â
0.00000603Â Â Â 0.00000016<br>
    atom  41 type 4  force =   -0.00001613  Â
0.00000196Â Â Â 0.00000515<br>
    atom  42 type 4  force =   -0.00000014  Â
0.00000820Â Â -0.00000460<br>
    atom  43 type 4  force =    0.00000091  Â
0.00000952Â Â Â 0.00001063<br>
    atom  44 type 4  force =    0.00000012 Â
-0.00000246Â Â Â 0.00000554<br>
    atom  45 type 4  force =    0.00000154  Â
0.00000256Â Â Â 0.00001045<br>
    atom  46 type 4  force =    0.00000846  Â
0.00000608Â Â -0.00000078<br>
    atom  47 type 4  force =    0.00000508 Â
-0.00000261Â Â Â 0.00001345<br>
    atom  48 type 4  force =    0.00000340  Â
0.00000050Â Â Â 0.00000619<br>
    atom  49 type 4  force =    0.00000354 Â
-0.00000332Â Â Â 0.00000588<br>
    atom  50 type 4  force =   -0.00000428  Â
0.00000637Â Â Â 0.00000854<br>
    atom  51 type 4  force =   -0.00000650 Â
-0.00000066Â Â -0.00000641<br>
<br>
    Total force =    0.000149    Total SCF correction
=Â Â Â Â 0.000000<br>
<br>
    bfgs converged in  4 scf cycles and  3 bfgs steps<br>
    (criteria: energy < 1.0E-06 Ry, force <Â
1.0E-15 Ry/Bohr)<br>
<br>
    End of BFGS Geometry Optimization<br>
</p>
<p><br>
<br>
</p>
</div>
<br>
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<br clear="all">
<br>
-- <br>
<div class="gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>Paolo Giannozzi, Dip. Scienze Matematiche
Informatiche e Fisiche,<br>
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy<br>
Phone +39-0432-558216, fax +39-0432-558222<br>
<br>
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