[Wien] calculation with lmbj potential

[Burhan Ahmed]

The 6ql slab is created with 1x1x2 supercell with vacuum in Z direction and
accepting repeat atoms at z=0 (using x supercell program). At first the x
supercell convert rhombohedral cell into hexagonal and then from hexagonal
cell I have created the 1x1x2 supercell and then I took the structure
suggested by sgroup.

Yes sorry for that I have used MSR1a method for the relaxation.

The force convergence is set to 1 Ry.

On Mon, 24 Jul, 2023, 2:06 pm Peter Blaha, <peter.blaha at tuwien.ac.at> wrote:

> I'm not sure how you get a non-stoichimetric cell with a multiplicative
> number of unit cells, unless you said you want to repeat the atom at z=0.
> Of course, without this extra layer, you may not have inversion and get
> 2 different surface terminations in one calculation. This is the usual
> problem of slabs.
> Also symmetry will be reduced and "multiplicity" errors occur. But both,
> nn and sgroup create new struct files where this has been corrected.
>
> If possible, I would also go to a smaller number of layers.
>
>
> Am 24.07.2023 um 10:13 schrieb Burhan Ahmed:
> > That is very true. I made the slab using the tutorial available in the
> > wien2k user manual by executing x-supercell program. What I found is
> > that the 6ql supercell consist of an extra Te atom. But whenever I try
> > to remove this atom I got multiplicity error. Sir, what is best possible
> > way of making slab with vacuum or surfaces??
> >
> > Thanks
> >
> > Regards
> >
> > Burhan Ahmed
> >
> > *Research Scholar, AUS *
> >
> > *From: *Laurence Marks <mailto:laurence.marks at gmail.com>
> > *Sent: *Saturday, July 22, 2023 6:30 PM
> > *To: *A Mailing list for WIEN2k users
> > <mailto:wien at zeus.theochem.tuwien.ac.at>
> > *Subject: *Re: [Wien] calculation with lmbj potential
> >
> > Others will probably give you suggestions about converging mBJ. Some
> > deeper comments.
> >
> > The most common reason that calculations behave badly is user error.
> > Sometimes this is doing the initialization wrong, often it is creating
> > an inappropriate model. Just because one can use x supercell or related
> > codes to create atomic positions does /not/ make them sensible.
> >
> > Your slab has a composition Bi12 Te19, i.e. it is Te rich. You therefore
> > have a reduced, n-type semiconductor with a small gap (about 0.1eV)
> > which will behave badly. If you look at your BVS you will see that atom
> > Te7 is severely underco-ordinated (unstable).
> >
> > I doubt that your slab will ever converge to anything which should be
> > published. Surfaces are not simple, it is unfortunately too easy to set
> > something up and get it wrong. (There are many papers in the literature
> > of dubious merit.)
> >
> > On Fri, Jul 21, 2023 at 10:47 PM Burhan Ahmed <burhan.ahmed at aus.ac.in
> > <mailto:burhan.ahmed at aus.ac.in>> wrote:
> >
> >     Dear experts, I am doing an scf calculation taking lmbj potential.
> >     My system is a slab of 6ql with a vacuum of 40 ang along c-axix.
> >     Whenever I try to run the scf calculation including SOC, after 999
> >     iteration the scf is still not converged. I have analyzed the scf
> >     file, it shows the fluctuating nature. At first the selected Rmt was
> >     2.5 then I reduces it to 2.34 and again convergence failed after 999
> >     cycle. I have included -hdlo and -lvns 8 switch in init_lapw as it
> >     shows heavy atom. I am attaching the case.struct file. Hoping for
> >     any suggestion/solution.
> >
> >     Regards
> >
> >     Burhan Ahmed
> >
> >     *Research Scholar, AUS *
> >
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> >
> >
> > --
> >
> > Professor Laurence Marks (Laurie)
> > Department of Materials Science and Engineering
> > Northwestern University
> > www.numis.northwestern.edu <http://www.numis.northwestern.edu>
> > "Research is to see what everybody else has seen, and to think what
> > nobody else has thought", Albert Szent-Györgyi
> >
> >
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> --
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
> Phone: +43-1-58801-165300
> Email: peter.blaha at tuwien.ac.at    WIEN2k: http://www.wien2k.at
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