[Wien] Need help; Supercell's folded band structure.

[Oleg Rubel]

Hello Youngboem,

it would be useful to include the band structure plots from your attempts. Otherwise it is hard to guess what went wrong.

Also, before plotting, it will be helpful to look at a part of the output that contains the Bloch spectrum weights for the conduction band maximum and the valence band minimum.

Fold2Boch runs in two modes complex (default) and real. In case your 2x2x2 supercell has the inversion symmetry (check structure file for a diagonal matrix with -1), you will need to activate the real version.


Thank you
Oleg

> On Oct 1, 2015, at 05:28, Peter Blaha <pblaha at theochem.tuwien.ac.at> wrote:
> 
> Clearly your solution is    fold2bloch.
> 
> If you don't like the plot, you have to modify this part yourself and make a different plot, but fold2bloch captures all the relevant physics which happens due to doping. Doping may lead to a "broadening" of bands when you introduce alloying (and represent it in the original BZ).
> 
> Otherwise you have to write your own code, but the basis will always be like fold2bloch (check their paper for some deeper understanding about "Bloch functions" and folding ....)
> http://arxiv.org/abs/1405.4218
> 
> 
> 
> On 10/01/2015 10:54 AM, Youngboem Cho wrote:
>> Hi. I can solve many technical problems by all your helps. Thank you
>> very much..!
>> Now new problem emerged in front of me.
>> Very simple problem but unfortunately, it's too hard to solve for me.
>> 
>> "How can I unfold the band structure made in 2x2x2 or some structure by
>> 'supercell'? (without fold2bloch)"
>> 
>> I guess that this folded band is caused by shortened reciprocal vectors.
>> For example, Ge's minimum conduction band's energy is located at L-valley.
>> but after I made it be 2x2x2 structure, lattice parameter is doubled
>> that it makes reciprocal vectors 1/2 shortened.
>> so when I calculate and see the 2x2x2 Ge's band structure, it look weird.
>> (Actually Ge's minimum conduction band's energy is located at L-valley
>> but this 2x2x2 shows me
>> weired location; Gamma-valley is the lowest conduction band energy!)
>> (I think maybe it misunderstood the true L-point. it just calculate
>> until L-point*1/2 and then finished. am I right?)
>> 
>> 1) So I doubled the 'm' in (m*kx m*ky m*kz)
>> but this made the band structure just folded.
>> 2) I used 'Fold2bloch'. but this doesn't seems beautiful for me
>> (I want to make 2x2x2's band structure just like 1x1x1's band structure.)
>> 
>> All this efforts are for alloy's band structures.
>> It seems to need use 'supercell' For under 1% of alloy. so I have to
>> solve this problem.
>> 
>> Is there any good suggestion?
>> 
>> thank you for reading!
>> 
>> 
>>                                                            - Sincerely
>> Youngboem Cho
>> 
>> 
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> 
> -- 
> 
>                                      P.Blaha
> --------------------------------------------------------------------------
> Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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