Dear Asad,
What is the benefit of using dipfield=.true.? Well, the benefit is that
you get the correct electronic structure,
energetics, and so on. As you want to simulate a 2D system with 3D
boundary conditions this is the only
correct way if you have an asymmetric system (in the z-direction,
assuming the 2D system is in xy). Well,
not the only correct way. Recently a Coulomb cutoff technique was
implemented in QE, check input flag
assume_isolated='2D'
Regards
Thomas
P.S.: If you have a dipole in your system you'll see that properties
(especially the total energy) will change
with increasing vacuum region. If you increase it, you'll minimize the
eigenfunction overlap between the
repeated layers but the Coulomb interaction will never be zero and thus
you can get wrong results - and
this will be worse for larger dipole, e.g., the flourinated graphene.
On 11/13/18 08:38, Asad Mahmood wrote:
Hi,
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?
I am using 20 angstrom vacuum between two layers to avoid mutual
influence.
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--
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: thomas.bru...@uni-leipzig.de
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