[Wien] External electric field (bias)

[Laurence Marks]

Quite probably your structure is inappropriate. In 99% of cases polarity is
compensated by structural rearrangements, and there is a known (but too
rarely considered) boundary condition that the sum of the Born charges at a
surface is zero, see https://doi.org/10.1103/PhysRevB.57.5742 and
https://doi.org/10.1103/PhysRevB.84.205432.

On Fri, Oct 10, 2025 at 1:05 PM Lukasz Plucinski <lukasz.galaxy.s3 at gmail.com>
wrote:

> Dear All,
>
> I have been trying to calculate a slab of a polar semiconductor.
> Unfortunately, there seems to be an effect of an electric field across the
> slab.
>
> I see that one can add external E field by including line 4 in case.in0
> file: "IFIELD, EFIELD, WFIELD". I understand that my slab should be
> positioned at around 1/4 of the unit cell (so, a lot of vacuum), to
> make use of the zig-zag potential.
>
> So far I calculated the slab (without E field), and I can see a ladder of
> bands, instead of something resembling the "projected bulk band structure".
> Is there a way to read some parameters from this slab, in order to have an
> educated guess for the "IFIELD, EFIELD, WFIELD" values?
>
> Best,
> Lukasz
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-- 
Emeritus Professor Laurence Marks (Laurie)
Northwestern University
Webpage <http://www.numis.northwestern.edu> and Google Scholar link
<http://scholar.google.com/citations?user=zmHhI9gAAAAJ&hl=en>
"Research is to see what everybody else has seen, and to think what nobody
else has thought", Albert Szent-Györgyi
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