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Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Thu Feb 24, 2011 3:11 pm
by riche
Dear all,
I have a problem in reproducing the bandstructure of Al by 4 atomic supercell.
First, I used 1 atomic supercell, and the resulting bandstructure agrees well with the literature. But I couldn't use 4 atomic supercell to reproduce the same results.
The k-points along high symmetry lines are exactly the same in the calculations of 1 and 4 atomic supercells as indicated in the OUTCAR files. To be specific, the k-points scaled by 2pi/a printed in the OUTCAR files are exactly the same.
Does anyone have any idea what is going on?
Thank you very much and best wishes!

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Thu Feb 24, 2011 6:33 pm
by alex
The trap you took is called Brillouin zone folding. bands are folded back into a smaller reciprocal cell.

Hth

alex

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Thu Feb 24, 2011 6:37 pm
by riche
Dear all,
This is just a very stupid mistake. How is it even possible for the results to be the same? I guess I figured out what I need to do.

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Thu Feb 24, 2011 6:40 pm
by riche
Dear Alex,
Thank you very much for your answer. How did I just forget the basics?
Thanks again and best wishes!

<span class='smallblacktext'>[ Edited Thu Feb 24 2011, 07:48PM ]</span>

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Fri Feb 25, 2011 7:37 am
by alex
:-) happens from time to time to myself, too. My trick is to go back a step and take a look again later.

Cheers,

alex

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Thu Jun 27, 2013 6:15 pm
by vaspfonda
I have a related question regarding the zone folding. The band of double unit cell in one dimensional structure is supposed to be similar to that of single unit cell simply by zone-folding (Pi/2a, Pi/a) to (0, Pi/2a). The eigenvalues should be the same. But I found some energy levels close to EF are shifted. Is this normal? Or I did something wrong?

Difference in the bandstructure of fcc Al by 1 and 4 atomic supercells

Posted: Sat Jul 13, 2013 7:57 am
by sumanali
Thank you for your answer dear lumacido. i think the kpoints you suggested can be used for relaxation of the surfaces. But as far as i know, i need to use specific kpoint coordinates to find a surface's band structure. For example 111 surface needs to set Gamma - M - K points and they have different coordinates.

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<span class='smallblacktext'>[ Edited Thu Jul 24 2014, 11:47AM ]</span>