[Wien] Re : band structure dependence on symmetry and complex calculation

[Rocquefelte]

The concept of backfolding is indeed at the origin of what you are 
seeing as explained by Peter.
Indeed, although the cell parameters are nearly the same in the two 
case.struct files, the WIEN2k calculation is not done in the same cell, 
because one structure is taking into account the F-centering.

Thus the F-centered system has 4 atoms only, while the P-centered system 
has 16 --> i.e. 4 times more.

In other words, you have 4 times more bands in your calculation in the 
P-centered case, and these bands come from backfolding of the bands 
obtained in the small cell (which contain only 4 atoms).

Regards

Xavier


Le 6/29/2013 12:46 PM, venkatesh chandragiri a écrit :
> Dear P. Blaha and Xavier.
>
> Thanks for your prompt replies on my doubt.
>
> Related to the reply of P. Blaha, it is noticed that in my case both 
> structure files are generated by using approximately same lattice 
> constant (Sorry to don't mention this in my earlier mail). Hence, as 
> the unit cell is not doubled, the concept of back folding may be ruled 
> out. Please, find the attached case.struct files for the details of 
> the two cases. I am waiting to listen your further comments on this..?
>
> In addition, as we known, the Brillouin zone for Fm3m space group is 
> truncated octahedron, while for P1 space group it is cubic type. The 
> case.klist_band file is generated from xcrysden for Fm3m space group 
> and the same case.klist_band file have been used for second case (P1 
> space group) also to define the k-point path. Is it cause any problem 
> related to my doubt.
>
> For the reference of Xavier, i have attached the case.struct files 
> related to the two casesalong with this mail.
>
> Your replies are very helpful to understand the things related to band 
> structure in the solids.
>
> regards,
>
> Ch. venkatesh.
>
>
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