[Wien] How to assign kz to slab bands?

[Rubel, Oleg]

Dear Lukasz ,

I am not aware of fold2Bloch ever being used for supercells with vacuum. So, you are welcome to try but I am skeptical (same as Peter). Another option would be to plot "fat" bands with a higher weight assigned to surface atoms.

Best regards,
Oleg

> -----Original Message-----
> From: Wien <wien-bounces at zeus.theochem.tuwien.ac.at> On Behalf Of Peter
> Blaha
> Sent: Sunday, February 25, 2024 12:33 PM
> To: wien at zeus.theochem.tuwien.ac.at
> Subject: Re: [Wien] How to assign kz to slab bands?
> 
> Caution: External email.
> 
> 
> Yes, I know.
> 
> But usually the model is to make a supercell (without vacuum) and put some
> impurity into it. Then you can fold the supercell back becaus it is a multiple of
> the small unit cell, and find bulk and impurity bands.
> 
> In your case, you don't have just a supercell, but a supercell + vacuum.
> Thus c' is not just 3 x c (for a cell with 3 unitcells in c direction), but vacuum has
> been added.
> 
> I don't know if backfolding would work in this case, maybe you can use the
> trick I mentioned last time.
> 
> Am 25.02.2024 um 12:45 schrieb pluto via Wien:
> > Dear Prof. Blaha,
> >
> > Thank you for the comment.
> >
> > fold2Bloch might be exactly what I need! There are papers where it is
> > mentioned in relation to ARPES.
> >
> > Best,
> > Lukasz
> >
> >
> >
> >
> >
> >
> > On 2024-02-24 16:05, Peter Blaha wrote:
> >> Hi,
> >>
> >> There is no automatic tool for this.
> >>
> >> I detected surface states by an analysis of the partial charges of
> >> the atoms in the various layers. A surface state should have charge
> >> only in the surface (maybe a bit in the subsurface layer).
> >>
> >> Note, there is   fold2bloch, which does backfolding of supercells, but
> >> I don't know what to do with the vacuum.
> >> One could try to give him a supercell in z direction without vacuum
> >> and still use the eigenvectors from the supercell+vacuum calculation,
> >> but it may give complete nonsense.
> >>
> >> Best regards
> >> Peter Blaha
> >>
> >> Am 23.02.2024 um 17:02 schrieb pluto via Wien:
> >>> Dear All,
> >>>
> >>> Everyone who has done a slab calculation knows that it contains some
> >>> surface states and some projected bulk bands.
> >>>
> >>> These projected bulk bands are typically nearly identical to the
> >>> bulk projected bands. If we have a 10ML slab, they will essentially
> >>> look like cutting the bulk BZ 10 times along kz. In case of bulk
> >>> bands obviously each cut is assigned to some kz.
> >>>
> >>> Now, we can compare bulk projected bands and slab bands, and then we
> >>> will more or less know which of the slab bands relate to which kz
> >>> (besides the surface states that don't have kz).
> >>>
> >>> Is there a simple way to automatically assign kz to the slab bands?
> >>>
> >>> One solution to this problem would be to calculate something like
> >>> <exp(ikz.r)|Psi(k_paral,E,r)>, which is essentially a Fourier
> >>> transform of the initial wave function for some energy and k_paral,
> >>> i.e. for one eigenvalue point in the band structure. Is that kind of
> >>> matrix element hidden somewhere in the WIEN2k output files?
> >>>
> >>> Actually, this would also assign kz to the surface states, which
> >>> could also be useful in the photoemission context.
> >>>
> >>> Best,
> >>> Lukasz
> >>> _______________________________________________
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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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