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<p>Hello Lucian,</p>
<p>is the slab in the center of the cell, or around z=0 ?</p>
<p>Anyway, the option assume_isolated='2D' modifies the Hartree
interaction, adding a cut-off smooth step function at half the
cell z-length, i.e. 1/r → step(z)/r. If a long-range 1/r^n
propagates outward from your slab, at half the cell distance you
will see the step function. As long as this happens in a region
where there is vacuum, it is not a problem.</p>
<p>kind regards<br>
</p>
<div class="moz-cite-prefix">On 24/06/2024 13:09, Lucian D. Filip
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:ff22e1ab-c597-4e93-b5ab-82e4990e8266@infim.ro">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<p>Hello,</p>
<p>I am looking at a PbTiO3 slab in vacuum. The slab is in a
polarized state and I am trying to obtain the Hartree potential
with the dipole correction applied. I have seen that the
assumed_isolated = '2D' option should do just that. However, I
do not understand the result I am getting. In the attached
picture I have plotted the Hartree potential averaged along the
z axis, for the polarized state and the centro-simmetric state
with polarization zero.</p>
<p>The slab is 5 PTO unit cells thick and there are 20 Angstroms
of vacuum on each side. The vacuum region is well above the
requirements of assume_isolated ='2D'. Can anyone explain two
things:</p>
<p>1) why are there two regions in vacuum looking like a
staircase.</p>
<p>2) why is there an electric field still present?</p>
<p><br>
</p>
<p>The weird artefacts at the edges of the supercell are due to
the averaging procedure (i am still working on it, not sure
where it is coming from).</p>
<p><br>
</p>
<p>Best regards,</p>
<p>Lucian<br>
</p>
<p><br>
</p>
<p><img src="cid:part1.3bnVUqNQ.aMkzP4Pb@cnrs.fr" alt="" class=""></p>
<pre class="moz-signature" cols="72">--
Dr. Lucian Dragos Filip
National Institute of Materials Physics
Atomistilor str. 405A, PO Box MG. 7
Magurele, 077125
Bucharest, Romania
E-mail: <a class="moz-txt-link-abbreviated moz-txt-link-freetext"
href="mailto:lucian.filip@infim.ro" moz-do-not-send="true">lucian.filip@infim.ro</a>
Website: <a class="moz-txt-link-freetext"
href="https://lucianfilip.wordpress.com/" moz-do-not-send="true">https://lucianfilip.wordpress.com/</a></pre>
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<div class="moz-signature">-- <br>
<small>Dr. Lorenzo Paulatto<br>
IdR @ IMPMC - CNRS UMR 7590 & Sorbonne Université<br>
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