# Re: [Wien] Need help; Can fold2Bloch unfold the band from K to K'?

```I wonder what is the k-mesh in the supercell that you use to get the path after
unfolding?```
```
Also, fold2Bloch will bring the k-points after unfolding in the range (-0.5,
0.5].

> (1/4 1/2 3/4) W

This cannot be found in the output since 3/4 > 0.5

> (0 1/2 1/2) X
> (-1/4 1/2 1/4) W

This should be possible to get. I did not test it, but the suggested k-path for
the supercell k-mesh would be

(0 0 0) - (-0.5, 0, 0.5)

Here is the rational for 2x2x2 supercell:

(KX, KY, KZ) -> (KX/2, KY/2, KZ/2) & ((KX+1)/2, KY/2, KZ/2) & ((KX+1)/2,
(KY+1)/2, KZ/2) & … total of 8 new k-points after unfolding

Say KX = 0.25 becomes after unfolding kx = 0.25/2 = 0.125 and kx = (0.25+1)/2 =
0.625 = 0.625-1 = -0.375
The last step (...-1) is needed if k-point goes out of bound (-0.5, 0.5].

Working backward, 1/2 will fold into 0 and 1/4 folds into 1/2. It is more
difficult to predict what happened to the points between X-W, but worth a try.

Oleg

> On Feb 2, 2016, at 22:02, Yongbeom Cho <jj2...@naver.com> wrote:
>
> I sent the figure to your e-mail that includes what I’m saying.
>
> My structure is 2:2:2.
>
> I can get the band structure from G to L or G to X.
> I set the vector
>
> (0 0 -1/2)
> (0 0 0)
> (0 0 1/2)
> (1/2 1/2 0)
> (-1/2 -1/2 0)
>
> But, I can’t get the band structure from W to L or W to X with fold2Bloch.
> I set the vector
>
> (1/4 1/2 3/4) W
> (0 1/2 1/2) X
> (-1/4 1/2 1/4) W
> (0 0 0) G
> (1/4 -1/2 -1/4) W
> (-1/4 -1/2 -3/4) X
> (1/4 1/2 3/4) W
> (0 0 1/2) L
> (0 0 -1/2) L
> (0 -1/2 -1/2) X
> (0 1/2 1/2) X
> (0 0 1/2) L
>
> When I try to unfold it, W to L and W to X band structure eliminated.
> What is the problem?
>
>
>
> Sincerely yours,
> Yongbeom Cho
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