<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
<div class="moz-cite-prefix">Hello<br>
</div>
<div class="moz-cite-prefix">What value are you using for conv_thr
in the electrons namelist ? You should use a value which is rather
lower than the default at least something like 1.d-9. It this is
the case the should be some warning just after the forces summary
at the end of each force computation. <br>
</div>
<div class="moz-cite-prefix">I hope this helps <br>
</div>
<div class="moz-cite-prefix">Pietro <br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">On 9/12/19 3:33 AM, Gui Wei wrote:<br>
</div>
<blockquote type="cite"
cite="mid:7a540e47.8ce8.16d231aa4f6.Coremail.weigui@cqu.edu.cn">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div>Dear QE users,</div>
<div><br>
</div>
<span style="white-space:pre"> </span>When I optimized the
structure of a heterostructure (containing about 130 atoms),it
does converges as expected,and there is basically no problem with
the atomic structure.The convergence threshold I used was <b>etot
conv thr: 2.0D-4</b> <b>forc_conv_thr:2.0D-3</b>.By comparing
with the parameter design in the literature (similar model，usually
using software VASP),I think this convergence accuracy is
relatively rough,especially force.So I raised the threshold to <b>etot
conv thr: 1.0D-4 </b> <b>forc_conv_thr:2.0D-3.</b>At this point
I found that the structure optimization could not converge.I
extracted the data from the output document and plotted Energy
difference-Scf cycles curve and Max force-Scf cycles curve.I found
that scf cycles =5 satisfies the convergence of the former rough
convergence(both energy and force).After that,two curves rise
synchronously,this means that the latter's fine convergence
accuracy will never be achieved.
<div><span style="white-space:pre"> </span>What I want to know is
whether the atomic structure under the rough precision can be
counted as a stable structure.If so, how do I understand the
rise of the above two curves (this seems to be that the
structure is not stable, in my understanding, if it is a stable
structure, the two curves should continue to slowly decline,
eventually reaching an almost horizontal state).If not, what is
the solution?
<div><br>
</div>
<div>
<div>Wei gui</div>
<div>School of Mechanical Engineering，Chongqing University,
China</div>
</div>
<div><br>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
</div>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
Quantum ESPRESSO is supported by MaX (<a class="moz-txt-link-abbreviated" href="http://www.max-centre.eu/quantum-espresso">www.max-centre.eu/quantum-espresso</a>)
users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a>
<a class="moz-txt-link-freetext" href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a></pre>
</blockquote>
<p><br>
</p>
</body>
</html>