[Wien] question about applying electric field in wien2k

[Laurence Marks]

With apologies to Peter, I would not say that the options are experimental.

If you are OK with handling Fortran, I suggest that you copy eramps.F then
comment out "subroutine tester" and uncomment "program tester". Then
compile run it.

Be careful that, due to truncation of the Fourier series, the actual
potential used is not, for instance, a true zig-zag but can have ripples.
Some of the other modes (taken from the literature) try to compensate for
this. You can use one of the potential output modes of lapw0 to see what
you really have; best to look at lapw0.F.

N.B., if you are using option 30 I would use atoms at z=0.25 and -0.25, and
a mirror along z. You will need to add slight distortions to avoid Wien2k
reducing the cell. This should be stable to translations along z which
could occur when doing MSR1a (-min) - fixed in the next release.

--
Professor Laurence Marks
Department of Materials Science and Engineering, Northwestern University
www.numis.northwestern.edu
"Research is to see what everybody else has seen, and to think what nobody
else has thought" Albert Szent-Györgyi

On Thu, Jan 5, 2023, 03:55 Peter Blaha <peter.blaha at tuwien.ac.at> wrote:

> I suggest you stay with the default mode (the other options are more
> experimental) and put IFIELD=30.
>
> This produces for EFELD=1.0 Ry a zig-zag potential along z of 0.5 (for
> z=0), -0.5 (for z=0.5) and again 0.5 for z=1.0.
>
> Thus you need to setup a slab with your atoms centered around z=0.25  and
> a vacuum thick enough so that you do not have atoms close to the kinks at
> Z=0 or z=0.5. Also make sure that you do not have inversion symmetry.
>
> PS: As you noticed, there is a small bug in WIEN2k_21 for the E-field
> option and it must be specified in the 5th line ! (Will be fixed in the new
> release).
>
>
> Am 04.01.2023 um 11:54 schrieb Zohreh Alsadat Nourbakhsh:
>
> Dear Wien2k admins and users
>
> I am using WIEN2k_21.1 on linux mint 21 (MATE 64-bit) mint code for apply
> external electric field to a two dimensional semimetal system.
> Unfortunatly, after following the userguide instructions, it seems that
> external electric has almost no effect on my electronic band structure.
>
> I have tried various values of IFIELD paramater (30, 8000, 10000, 11000,
> 12000), but the expected splitting in the band crossing did not happen. I
> also tried a lot to reproduce the calculations in the results of the
> article (https://doi.org/10.1016/j.physe.2012.04.017) on bilayer
> graphene, but I failed to observe the reported spliiting after applying
> electric field.
>
> my case.in0 input file for electric filed application:
>
> TOT  XC_PBE     (XC_LDA,XC_PBESOL,XC_WC,XC_MBJ,XC_SCAN)
>
> NR2V      IFFT      (R2V)
>    18   18  216    2.00  1 NCON 9  # min IFFT-parameters, enhancement
> factor, iprint, NCON n
> 8000 0.3
> 8000 0.3
>
> Your kind help is highly appreciarted.
>
>           Best Regards
>
>           Z.Nourbakhsh
>
>
>
> _______________________________________________
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>
> --
> -----------------------------------------------------------------------
> Peter Blaha,  Inst. f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-158801165300
> Email: peter.blaha at tuwien.ac.at
> WWW:   http://www.imc.tuwien.ac.at      WIEN2k: http://www.wien2k.at
> -------------------------------------------------------------------------
>
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