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Dear Gui,<br>
<br>
in addition to the point mentioned by Lorenzo, I wonder if your
c-axis is large enough...<br>
Let's say you calculate the Fe(110) surface by 3 layers, which is a
good starting point but<br>
might be not enough, your system has a thickness of about 10
Angstrom - 2 times the<br>
lattice spacing of Fe(110) plus the spacing iron-graphene plus the
graphene-oxygen distance.<br>
This leaves 15 Angstrom or less for the distance between the
repeated slabs. This seems<br>
rather small to me even if it might be enough. Additionally, you
could have a dipole in your<br>
system due to charge transfer and thus you should add the dipole
correction. Especially,<br>
the dipole could play an important role in the correct adsorption
energy and geometry<br>
and thus also for the convergence of forces.<br>
<br>
Regards<br>
<br>
Thomas<br>
<br>
<div class="moz-cite-prefix">On 3/6/19 10:02 AM, Gui Wei wrote:<br>
</div>
<blockquote type="cite"
cite="mid:79c68d66.b89.169523dccf4.Coremail.201707021019@cqu.edu.cn">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div>Dear QE users,</div>
<div>I am trying to optimize the adsorption system that contain
Fe(110) substrate and single-layer graphene connected to an
oxygen atom.I got the total force and the energy like this.At
first, everything was fine,but after 0.006846 the total force
began to increase ,causing the total force not to converge ,it
is a extremely strange result.Is there any way to solve this
problem?</div>
<div><br>
</div>
<div>Any suggestions would be greatly appreciated.</div>
<div>Thank you.</div>
<div><br>
</div>
<div><br>
</div>
<div>Total force = 0.316790 energy new =
-4107.2627566975 Ry</div>
<div>Total force = 0.246608 energy new =
-4107.3151393348 Ry</div>
<div>Total force = 0.156503 energy new =
-4107.3635865834 Ry</div>
<div>Total force = 0.119628 energy new =
-4107.3895957292 Ry</div>
<div>Total force = 0.078444 energy new =
-4107.3969303863 Ry</div>
<div>Total force = 0.052366 energy new =
-4107.4017754787 Ry</div>
<div>Total force = 0.040309 energy new =
-4107.4042249914 Ry</div>
<div>Total force = 0.033754 energy new =
-4107.4058726129 Ry</div>
<div>Total force = 0.028026 energy new =
-4107.4071437156 Ry</div>
<div>Total force = 0.025319 energy new =
-4107.4081667548 Ry</div>
<div>Total force = 0.024093 energy new =
-4107.4089392392 Ry</div>
<div>Total force = 0.022277 energy new =
-4107.4096467799 Ry</div>
<div>Total force = 0.019561 energy new =
-4107.4102126980 Ry</div>
<div>Total force = 0.016523 energy new =
-4107.4106348116 Ry</div>
<div>Total force = 0.014292 energy new =
-4107.4109663982 Ry</div>
<div>Total force = 0.013121 energy new =
-4107.4112149183 Ry</div>
<div>Total force = 0.011934 energy new =
-4107.4114021825 Ry</div>
<div>Total force = 0.011261 energy new =
-4107.4115692713 Ry</div>
<div>Total force = 0.010521 energy new =
-4107.4117253881 Ry</div>
<div>Total force = 0.009179 energy new =
-4107.4118535327 Ry</div>
<div>Total force = 0.008233 energy new =
-4107.4119532022 Ry</div>
<div>Total force = 0.007949 energy new =
-4107.4120378076 Ry</div>
<div>Total force = 0.007614 energy new =
-4107.4121212783 Ry</div>
<div>Total force = 0.007100 energy new =
-4107.4121953505 Ry</div>
<div>Total force = 0.006846 energy new =
-4107.4122538477 Ry</div>
<div>Total force = 0.006967 energy new =
-4107.4123143593 Ry</div>
<div>Total force = 0.007559 energy new =
-4107.4123893617 Ry</div>
<div>Total force = 0.007912 energy new =
-4107.4124672492 Ry</div>
<div>Total force = 0.007587 energy new =
-4107.4125386594 Ry</div>
<div>Total force = 0.007532 energy new =
-4107.4126143150 Ry</div>
<div>Total force = 0.008046 energy new =
-4107.4126949028 Ry</div>
<div>Total force = 0.008145 energy new =
-4107.4127766088 Ry</div>
<div>Total force = 0.008142 energy new =
-4107.4128651944 Ry</div>
<div>Total force = 0.009356 energy new =
-4107.4129774552 Ry</div>
<div>Total force = 0.011161 energy new =
-4107.4131286975 Ry</div>
<div>Total force = 0.012473 energy new =
-4107.4133389405 Ry</div>
<div>Total force = 0.013542 energy new =
-4107.4136064842 Ry</div>
<div>Total force = 0.014769 energy new =
-4107.4138982197 Ry</div>
<div>Total force = 0.015571 energy new =
-4107.4142168735 Ry</div>
<div>Total force = 0.015344 energy new =
-4107.4145642683 Ry</div>
<div>Total force = 0.015134 energy new =
-4107.4149145704 Ry</div>
<div>Total force = 0.016511 energy new =
-4107.4152819587 Ry</div>
<div>Total force = 0.016788 energy new =
-4107.4156041418 Ry</div>
<div><br>
</div>
<div><br>
</div>
<div> &control</div>
<div> calculation = 'relax',</div>
<div> prefix='epoxy1',</div>
<div> restart_mode='from_scratch' </div>
<div> pseudo_dir = '/public/home/duan1/GuiWei/pseudo/',</div>
<div> outdir='/public/home/duan1/GuiWei/tempdir/'</div>
<div> tstress = .true.</div>
<div> tprnfor = .true.</div>
<div> etot_conv_thr=1.0D-4</div>
<div> forc_conv_thr=1.0D-3</div>
<div>/</div>
<div> &system </div>
<div> ibrav= 0, </div>
<div> nat=125, </div>
<div> ntyp=3,</div>
<div> nspin = 2 </div>
<div> starting_magnetization(1) =0.4 </div>
<div> occupations='smearing',</div>
<div> smearing='mp',</div>
<div> degauss=0.02,</div>
<div> ecutwfc =37.0</div>
<div> ecutrho =300.0 </div>
<div> vdw_corr='DFT-D' </div>
<div> london_s6 = 0.75</div>
<div>/</div>
<div>&electrons</div>
<div> conv_thr = 1.0d-8</div>
<div> mixing_beta = 0.2</div>
<div> mixing_mode = 'local-TF'</div>
<div> mixing_ndim=16</div>
<div> electron_maxstep=200</div>
<div>/</div>
<div>&IONS</div>
<div> ion_dynamics='bfgs'</div>
<div>/</div>
<div>CELL_PARAMETERS angstrom</div>
<div>19.68000000000000 0.000000000000011
0.000000000000000</div>
<div>0.000000000000000 8.521689973238880
0.000000000000000</div>
<div>0.000000000000000 0.000000000000000
25.00000000000000</div>
<div>ATOMIC_SPECIES</div>
<div>Fe 55.847 Fe.pbe-nd-rrkjus.UPF</div>
<div>C 12.0107 C.pbe-rrkjus.UPF</div>
<div>O 16.00 O.pbe-rrkjus.UPF</div>
<div>ATOMIC_POSITIONS crystal</div>
<div>......</div>
<div>K_POINTS automatic</div>
<div>2 2 1 0 0 0</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div><br>
</div>
<div>
<div>Wei gui</div>
<div>School of Mechanical Engineering，Chongqing University,
China</div>
</div>
<div><br>
</div>
<div><br>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
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</blockquote>
<br>
<pre class="moz-signature" cols="72">--
Dr. rer. nat. Thomas Brumme
Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry
Leipzig University
Phillipp-Rosenthal-Strasse 31
04103 Leipzig
Tel: +49 (0)341 97 36456
email: <a class="moz-txt-link-abbreviated" href="mailto:thomas.brumme@uni-leipzig.de">thomas.brumme@uni-leipzig.de</a>
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