[Wien] How to assign kz to slab bands?

[Peter Blaha]

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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-- 
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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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