<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<br><span style="font-family:arial,helvetica,sans-serif"><br></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 <br>contain too much numerical noise for the minimization to be effective. <br>Not sure why it performs a further step.<br></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<br></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"><br></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">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">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> 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> Forces acting on atoms (cartesian axes, Ry/au):<br>
<br>
atom 1 type 1 force = 0.00000940 0.00000005
0.00000759<br>
atom 2 type 1 force = 0.00003922 -0.00005066
-0.00003891<br>
atom 3 type 1 force = -0.00000527 -0.00001786
-0.00000047<br>
atom 4 type 1 force = 0.00000695 -0.00000525
-0.00000490<br>
atom 5 type 1 force = 0.00000837 0.00000136
0.00000695<br>
atom 6 type 1 force = -0.00000139 0.00000800
-0.00000768<br>
atom 7 type 1 force = -0.00000042 -0.00000074
-0.00000888<br>
atom 8 type 1 force = -0.00002354 -0.00001155
-0.00003861<br>
atom 9 type 1 force = 0.00001305 -0.00001546
0.00000555<br>
atom 10 type 1 force = -0.00001756 0.00002269
-0.00001184<br>
atom 11 type 1 force = -0.00000255 -0.00001734
0.00001741<br>
atom 12 type 1 force = 0.00001174 0.00001759
-0.00001735<br>
atom 13 type 1 force = -0.00000633 -0.00000979
0.00000484<br>
atom 14 type 1 force = -0.00001325 0.00001294
-0.00000493<br>
atom 15 type 1 force = 0.00000782 -0.00002956
-0.00000586<br>
atom 16 type 1 force = -0.00000317 0.00001363
0.00000878<br>
atom 17 type 1 force = -0.00002203 0.00000270
-0.00000480<br>
atom 18 type 1 force = -0.00000998 0.00000531
0.00001788<br>
atom 19 type 1 force = 0.00000060 -0.00000321
-0.00001756<br>
atom 20 type 1 force = -0.00000688 0.00002017
0.00000404<br>
atom 21 type 1 force = -0.00000129 -0.00000416
-0.00001532<br>
atom 22 type 2 force = -0.00000319 -0.00000167
0.00000395<br>
atom 23 type 2 force = 0.00001103 0.00001040
0.00000626<br>
atom 24 type 2 force = 0.00000396 -0.00000186
0.00000201<br>
atom 25 type 3 force = -0.00001044 0.00000478
-0.00000086<br>
atom 26 type 3 force = -0.00001291 0.00000415
-0.00000411<br>
atom 27 type 3 force = 0.00001756 -0.00000296
0.00000913<br>
atom 28 type 4 force = -0.00001578 0.00000879
0.00000423<br>
atom 29 type 4 force = -0.00001227 0.00000946
-0.00000839<br>
atom 30 type 4 force = 0.00001416 0.00001301
0.00001436<br>
atom 31 type 4 force = 0.00001660 -0.00000202
0.00000659<br>
atom 32 type 4 force = 0.00003452 -0.00001067
0.00001793<br>
atom 33 type 4 force = 0.00000938 -0.00001056
0.00000237<br>
atom 34 type 4 force = -0.00001496 -0.00000472
0.00000305<br>
atom 35 type 4 force = -0.00001625 -0.00000739
-0.00000918<br>
atom 36 type 4 force = 0.00001063 0.00001606
-0.00000310<br>
atom 37 type 4 force = -0.00000110 0.00000394
-0.00000268<br>
atom 38 type 4 force = -0.00000163 0.00000039
0.00000700<br>
atom 39 type 4 force = -0.00000066 -0.00000016
0.00000132<br>
atom 40 type 4 force = -0.00000813 0.00000603
0.00000016<br>
atom 41 type 4 force = -0.00001613 0.00000196
0.00000515<br>
atom 42 type 4 force = -0.00000014 0.00000820
-0.00000460<br>
atom 43 type 4 force = 0.00000091 0.00000952
0.00001063<br>
atom 44 type 4 force = 0.00000012 -0.00000246
0.00000554<br>
atom 45 type 4 force = 0.00000154 0.00000256
0.00001045<br>
atom 46 type 4 force = 0.00000846 0.00000608
-0.00000078<br>
atom 47 type 4 force = 0.00000508 -0.00000261
0.00001345<br>
atom 48 type 4 force = 0.00000340 0.00000050
0.00000619<br>
atom 49 type 4 force = 0.00000354 -0.00000332
0.00000588<br>
atom 50 type 4 force = -0.00000428 0.00000637
0.00000854<br>
atom 51 type 4 force = -0.00000650 -0.00000066
-0.00000641<br>
<br>
Total force = 0.000149 Total SCF correction =
0.000000<br>
<br>
bfgs converged in 4 scf cycles and 3 bfgs steps<br>
(criteria: energy < 1.0E-06 Ry, force < 1.0E-15
Ry/Bohr)<br>
<br>
End of BFGS Geometry Optimization<br>
</p>
<p><br>
<br>
</p>
</div>
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