<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>Dear Minoru,</p>
<p>Thank you very much for taking the time to explain these examples
in detail. If you don't mind I have a few followup questions:</p>
<p>1) for the first case, the ESM calculation: how does one
determine the vacuum region? In a regular slab calculation, as far
as my understanding goes, one increases the vacuum region until
there is little interaction between the periodical neighbors as it
were. In this case, I have performed two calculations for 10 A of
vacuum on either side of the slab and then for 5 A. The latter
case had a lower total energy than the former. Is this normal? I
have also tried a rather large 30 A on either side, but the
calculation failed to converge.</p>
<p>2) also for the ESM case: do I understand correctly that for the
metal-slab-metal case, one controls the Hartree potential using
esm_efield and for the vacuum-slab-metal case one uses the
tot_charge parameter?</p>
<p>I am trying to make that the Hartree potential for my slab with
ferroelectric layers is correct as the following article suggests:</p>
<p><a class="moz-txt-link-freetext" href="https://www.nature.com/articles/s41524-021-00529-1">https://www.nature.com/articles/s41524-021-00529-1</a></p>
<p>They are using a different method and I believe that a
combination of ESM and FCP could accomplish the same result for my
case. That is why my next question is regarding FCP:</p>
<p>3) in FCP one has to provide the target_mu. In your example you
use the Fermi level from the ESM calculation in the first example
as the target mu in the FCP calculation. Is this the route that
must be used? <br>
</p>
<p><br>
</p>
<p>Thank you again for your time!</p>
<p><br>
</p>
<p>Best regards,</p>
<p><br>
</p>
<p>Lucian<br>
</p>
<div class="moz-cite-prefix">On 11/04/2022 16:16, Otani Minoru
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:D64A5FEF-D4B1-4D0E-922D-028630FDF831@ccs.tsukuba.ac.jp">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<div dir="auto" style="word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">Dear Lucian,
<div class=""><br class="">
</div>
<div class="">I made those examples in PW/examples/ESM_example
directory. Here, I am going to explain the purpose of each
examples.</div>
<div class=""><br class="">
</div>
<div class="">1) ESM</div>
<div class="">One can understand the overall usage of the
effective screening medium (ESM) method. More precisely, when
you plot the esm1 file, you can see the difference of the
calculated electrostatic potentials depending on the boundary
conditions, i.e., pbc, bc1, bc2, and bc3. By changing the
parameter "tot_charge", you can see how the Fermi energy
changes in a Constant-N calculation: Constant-N means that we
fix the total number of electron (N) during the SCF
calculation. If you want to understand more detail about the
method and configuration of the slab model, please read the
original paper:</div>
<div class="">Physical Review B 73, 115407 (2006)</div>
<div class=""><br class="">
</div>
<div class="">2) FCP & 3) GCSCF</div>
<div class="">Unlike the Constant-N calculation, the second
(FCP) and the third (GCSCF) examples, we can conduct an
electronic structure calculation with fixed chemical potential
for electron (constant-mu). FCP stands for fictitious charge
particle and the original paper is the following:</div>
<div class="">
<div style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0);"
class="">Physical Review Letters 109, 266101 (2012).</div>
</div>
<div class="">GCSCF is the abbreviation for the grand canonical
SCF and the original paper is below:</div>
<div class="">J. Chem. Phys. 146, 114104 (2017).</div>
<div class=""><br class="">
</div>
<div class="">You can find the difference between FCP and GCSCF
calculations in the following paper:</div>
<div class="">Physical Review Materials 5, 065001 (2021).</div>
<div class="">As stated in the paper, FCP and GCSCF have their
advantages in the constant-mu calculations. Thus we have
implemented both methods for users convenience. </div>
<div class=""><br class="">
</div>
<div class="">Best regards,</div>
<div class="">Minoru</div>
<div class=""><br class="">
</div>
<div class="">
<div class="">
<meta charset="UTF-8" class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color:
rgb(0, 0, 0); letter-spacing: normal; text-align: start;
text-indent: 0px; text-transform: none; white-space:
normal; word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap: break-word;
-webkit-nbsp-mode: space; line-break: after-white-space;"
class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color:
rgb(0, 0, 0); letter-spacing: normal; text-align: start;
text-indent: 0px; text-transform: none; white-space:
normal; word-spacing: 0px; -webkit-text-stroke-width:
0px; text-decoration: none; word-wrap: break-word;
-webkit-nbsp-mode: space; line-break:
after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0); color:
rgb(0, 0, 0); letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform: none;
white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration: none;
word-wrap: break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0);
color: rgb(0, 0, 0); letter-spacing: normal;
text-align: start; text-indent: 0px; text-transform:
none; white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px; text-decoration:
none; word-wrap: break-word; -webkit-nbsp-mode:
space; line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0);
color: rgb(0, 0, 0); letter-spacing: normal;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap: break-word;
-webkit-nbsp-mode: space; line-break:
after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0, 0);
color: rgb(0, 0, 0); letter-spacing: normal;
text-align: start; text-indent: 0px;
text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width:
0px; text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0,
0); color: rgb(0, 0, 0); letter-spacing:
normal; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal;
word-spacing: 0px; -webkit-text-stroke-width:
0px; text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0, 0,
0); color: rgb(0, 0, 0); letter-spacing:
normal; text-align: start; text-indent: 0px;
text-transform: none; white-space: normal;
word-spacing: 0px;
-webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0,
0, 0); color: rgb(0, 0, 0);
letter-spacing: normal; text-align: start;
text-indent: 0px; text-transform: none;
white-space: normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color: rgb(0,
0, 0); color: rgb(0, 0, 0);
letter-spacing: normal; text-align:
start; text-indent: 0px; text-transform:
none; white-space: normal; word-spacing:
0px; -webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;" class="">
<div dir="auto" style="caret-color:
rgb(0, 0, 0); color: rgb(0, 0, 0);
letter-spacing: normal; text-align:
start; text-indent: 0px;
text-transform: none; white-space:
normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode: space;
line-break: after-white-space;"
class="">
<div dir="auto" style="caret-color:
rgb(0, 0, 0); color: rgb(0, 0, 0);
letter-spacing: normal; text-align:
start; text-indent: 0px;
text-transform: none; white-space:
normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode:
space; line-break:
after-white-space;" class="">--------------------------------------------------------------------------------------------------------<br
class="">
Minoru Otani, Ph.D., Professor<br
class="">
Center for Computational Sciences
and Faculty of Pure and Applied
Sciences, <br class="">
University of Tsukuba, 1-1-1
Tennodai, Tsukuba, Ibaraki 305-8577,
Japan<br class="">
TEL: +81-29-853-4273<br class="">
FAX: +81-29-853-6406<br class="">
<a
href="mailto:otani@ccs.tsukuba.ac.jp"
class="" moz-do-not-send="true">E-mail:
otani@ccs.tsukuba.ac.jp</a></div>
<div dir="auto" style="caret-color:
rgb(0, 0, 0); color: rgb(0, 0, 0);
letter-spacing: normal; text-align:
start; text-indent: 0px;
text-transform: none; white-space:
normal; word-spacing: 0px;
-webkit-text-stroke-width: 0px;
text-decoration: none; word-wrap:
break-word; -webkit-nbsp-mode:
space; line-break:
after-white-space;" class="">Web: <a
href="https://www2.ccs.tsukuba.ac.jp/public/otani/"
class="moz-txt-link-freetext"
moz-do-not-send="true">https://www2.ccs.tsukuba.ac.jp/public/otani/</a><br
class="">
--------------------------------------------------------------------------------------------------------<br
class="">
<br class="">
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Apr 11, 2022, at 15:48, Lucian D. Filip
<<a href="mailto:lucian.filip@infim.ro"
class="moz-txt-link-freetext" moz-do-not-send="true">lucian.filip@infim.ro</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
<div class="">Hello all,<br class="">
<br class="">
Is there a tutorial out there that explains in detail
how to use the FCP method? I have read the one in the
PW/examples on github but I can't figure out what it
is trying to accomplish.<br class="">
<br class="">
It is split into three types of calculations: 1) ESM
calculation; 2) FCP calculation; 3) GCSCP calculation.
Why is that? Are they related? Is this the order one
is supposed to use to obtain a what exactly?<br
class="">
<br class="">
Can someone explain the purpose of each steps taken in
this example?<br class="">
<br class="">
<br class="">
Thank you!<br class="">
<br class="">
<br class="">
Lucian<br class="">
<br class="">
-- <br class="">
Dr. Lucian Dragos Filip<br class="">
National Institute of Materials Physics<br class="">
Atomistilor str. 405A<br class="">
PO Box MG. 7<br class="">
Magurele, 077125<br class="">
Bucharest, Romania<br class="">
<a href="mailto:lucian.filip@infim.ro" class=""
moz-do-not-send="true">E-mail:
lucian.filip@infim.ro</a><br class="">
Website: <a class="moz-txt-link-freetext" href="http://lucianfilip.wordpress.com">http://lucianfilip.wordpress.com</a><br class="">
<br class="">
_______________________________________________<br
class="">
The Quantum ESPRESSO community stands by the Ukrainian<br
class="">
people and expresses its concerns about the
devastating<br class="">
effects that the Russian military offensive has on
their<br class="">
country and on the free and peaceful scientific,
cultural,<br class="">
and economic cooperation amongst peoples<br class="">
_______________________________________________<br
class="">
Quantum ESPRESSO is supported by MaX
(<a class="moz-txt-link-abbreviated" href="http://www.max-centre.eu">www.max-centre.eu</a>)<br class="">
users mailing list <a class="moz-txt-link-abbreviated" href="mailto:users@lists.quantum-espresso.org">users@lists.quantum-espresso.org</a><br
class="">
<a class="moz-txt-link-freetext" href="https://lists.quantum-espresso.org/mailman/listinfo/users">https://lists.quantum-espresso.org/mailman/listinfo/users</a></div>
</div>
</blockquote>
</div>
<br class="">
</div>
</div>
<br>
<fieldset class="moz-mime-attachment-header"></fieldset>
<pre class="moz-quote-pre" wrap="">_______________________________________________
The Quantum ESPRESSO community stands by the Ukrainian
people and expresses its concerns about the devastating
effects that the Russian military offensive has on their
country and on the free and peaceful scientific, cultural,
and economic cooperation amongst peoples
_______________________________________________
Quantum ESPRESSO is supported by MaX (<a class="moz-txt-link-abbreviated" href="http://www.max-centre.eu">www.max-centre.eu</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>
<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" href="mailto:lucian.filip@infim.ro">lucian.filip@infim.ro</a>
Website: <a class="moz-txt-link-freetext" href="http://lucianfilip.wordpress.com">http://lucianfilip.wordpress.com</a></pre>
</body>
</html>