[Wien] Constrained DFT for excited state calculations

[Guoping Zhang]

 Dear Dr. Hashemifar,

My answer might be slightly too late, but might be of some help to you. You
can take a look at our papers J. Phys.: Condens. Matter 27 (2015) 206003
(7pp) and Journal of Magnetism and Magnetic Materials 563 (2022) 169885.
This can be done.

Our implementation is to change  the lapw2 codes so that the weightfile
read into the code is  replaced by your desired weight file. There are
three places that Wien code reads in the same weight files. I did not
change the latest codes.  When you try to fill some conduction bands and
remove some electrons from valence bands, give some broadening because the
self-consistent iteration at the next step may have a strong charge
fluctuation, which affects convergence. We tested both statically and
dynamically with a laser pulse, and found Wien2k is very stable. If
necessary, reducing the mixing in case.inm file. Sometimes, we also reduce
the convergence criterion, which must be checked carefully.

Best wishes,

Guoping



On Wed, Jun 14, 2023 at 2:34 PM Seyed Javad Hashemifar <hashemifar at iut.ac.ir>
wrote:

> sounds interesting, thank you!
> ---
> ------------------------------
> S. Javad Hashemifar, PhD
> Professor, Department of Physics
> Isfahan University of Technology, Iran
> Personal web page: https://hashemifar.iut.ac.ir
>
>
> On 2023-06-14 19:56, Peter Blaha wrote:
>
> It depends, but when you are lucky and have a reasonable gap: yes.
>
> modify case.in2  and reduce NE by one.
>
> copy case.in1 to case.in1sc, and the same with case.in2
>
> edit case.in2sc and increase NE by 2 (by one of the original) and put Emin
> to the previous (scf)  EFermi.
>
> run_lapw ...
>
> In this way you get two densities, one of NE-1 electrons and one with 1
> electron.
>
> However, EF may change and you may have to adapt Emin during this scf
> cycle.
>
> One would need to change the code and read a NBAND_min, ....
>
> PS: I tried this once but failed, because I wanted to occupy the "LUMO"
> state, which was of p-y character. My hope was, that this would lead to
> forces and move the atom somewhere else. However, during occupation of this
> py state it got shifted up in energy and another orbital became the "LUMO",
> so my relaxation was not due to this additional py electron, but something
> else ....
>
>
> Am 14.06.2023 um 17:09 schrieb Seyed Javad Hashemifar:
>
> Dear Wien2k developers and users
>
> Is  Wien2k able to perform constrained DFT calculations for excited states
> study?
>
> More specifically, I want to empty the Nth state and occupy the (N+1)th
> level.
>
> Bests
>
> S. Javad Hashemifar
>
>
> --
> ------------------------------
> S. Javad Hashemifar, PhD
> Professor, Department of Physics
> Isfahan University of Technology, Iran
> Personal web page: https://hashemifar.iut.ac.ir
>
>
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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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