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

Message

riche · #1 Post by **riche** » Thu Feb 24, 2011 3:11 pm

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!

alex · #2 Post by **alex** » Thu Feb 24, 2011 6:33 pm

The trap you took is called Brillouin zone folding. bands are folded back into a smaller reciprocal cell.

Hth

alex

riche · #3 Post by **riche** » Thu Feb 24, 2011 6:37 pm

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.

riche · #4 Post by **riche** » Thu Feb 24, 2011 6:40 pm

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>

alex · #5 Post by **alex** » Fri Feb 25, 2011 7:37 am

:-) happens from time to time to myself, too. My trick is to go back a step and take a look again later.

Cheers,

alex

vaspfonda · #6 Post by **vaspfonda** » Thu Jun 27, 2013 6:15 pm

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?

sumanali · #7 Post by **sumanali** » Sat Jul 13, 2013 7:57 am

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>