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Dear Asad,<br>
<br>
What is the benefit of using dipfield=.true.? Well, the benefit is
that you get the correct electronic structure,<br>
energetics, and so on. As you want to simulate a 2D system with 3D
boundary conditions this is the only<br>
correct way if you have an asymmetric system (in the z-direction,
assuming the 2D system is in xy). Well,<br>
not the only correct way. Recently a Coulomb cutoff technique was
implemented in QE, check input flag<br>
assume_isolated='2D'<br>
<br>
Regards<br>
<br>
Thomas<br>
<br>
P.S.: If you have a dipole in your system you'll see that properties
(especially the total energy) will change<br>
with increasing vacuum region. If you increase it, you'll minimize
the eigenfunction overlap between the<br>
repeated layers but the Coulomb interaction will never be zero and
thus you can get wrong results - and<br>
this will be worse for larger dipole, e.g., the flourinated
graphene.<br>
<br>
<div class="moz-cite-prefix">On 11/13/18 08:38, Asad Mahmood wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAPKVScyeFxRp5ssS7iwAu4ABDY-GfxK+HRAjHyLspsRS+LXVvQ@mail.gmail.com">
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<div dir="auto">Hi,
<div dir="auto"><br>
</div>
<div dir="auto">I have a hexagonal graphene(or any other)
monolayer and I hydrogenate(or flourinate, etc.) on the top
surface only (single sided). Is there need to use flag
dipfield = .true ? What is benefit or disadvantage of using
this flag for optimization of L.C or bond length?</div>
<div dir="auto">I am using 20 angstrom vacuum between two layers
to avoid mutual influence.</div>
</div>
<br>
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<br>
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<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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