[Wien] case.klist_band for band structure calculation having R-3c spacegroup

saurabh singh saurabhiitmandi at gmail.com
Mon May 16 08:50:32 CEST 2016


Thank you so much Peter BLAHA Sir for your valuable suggestion .
I have another query, In the Bilbao crystallographic server the k-vector
description is given in the two basis i.e. *Primitive basis and  **Conventional
basis *. In the user manual of Wien2k section 7.5.3 page 120, ix,iy,iz,
defines the k-vector, where x= ix/idv etc. We use cartesian coordinates in
units of 2π/a, 2π/b, 2π/c for P,C,F and B cubic, tetragonalnand
orthorhombic lattices, but internal coordinates for H and
monoclinic/triclinic lattices.
For rhombohedral there is no suggestion given.
Since we need to select the k-point manually in the xcrysden for high
symmetric k-point, therefore it is very important to choose the correct
basis coordinate. therefore I would like to know that in general for
Rhombohedral space group, which basis coordinate (Primitive or
Conventional) given in the Bilbao server should be used for making the
case.klist_band.
 I have two choice in xcrysden:
1. Primitive Brillouin zone: if I choose this option in xcrysden to select
the k-point coordinate then should i use the primitive basis coordinate of
high k-point from the Bilbao server.
2. Conventional Brillouin zone: for this should i use the conventional
basis coordinate from the Bilbao server.

Please give your suggestion for choosing the proper basis coordinate of
k-point for rhmbohedral lattice from Bilbao server.

On Sun, May 15, 2016 at 10:48 PM, saurabh singh <saurabhiitmandi at gmail.com>
wrote:

> Dear All Wien2k users,
>
> We want to calculate the band structure of LaCoO3 compound. The space
> group of this compound is R-3c (No. 167). In the Wien2k user manual, it is
> suggested for R lattice to use rhombohedral coordinates. Therefore we made
> the case.structure file using lattice parameters a=b= 10.2541 Bohr, c=
> 24.5494, alpha=beta=90 degree, gamma = 120 degree, and converted
> rhombohedral coordinates for each atom. When we try to make case.klist_band
> file by selecting the case.structure folder path in xcrysden, it says " the
> guessed bravais lattice type: not supported (the XSF's group number is 7).
> We tried the two different way to get the case.klist_band as follows:
>
> 1) Firstly, we have changed the lattice parameters in case.structure file
> in accordance to rhombohedral structure. We thought if the lattice
> parameters and atomic coordinate both will be accordance to rhombohedral
> then xcrysden can recognize the case.struct file. But again case.struct
> file does not recognized by xcrysden.
>
> 2) Secondly, we took the hcp.klist file given in wien2k SRC folder, which
> is as follows:
> GAMMA  0    0    0   40  2.0-0.5 1.5       Template for hcp structure
>               1    0    0   40  2.0
>               2    0    0   40  2.0
>               3    0    0   40  2.0
>               4    0    0   40  2.0
>               5    0    0   40  2.0
>               6    0    0   40  2.0
>               7    0    0   40  2.0
>               8    0    0   40  2.0
>               9    0    0   40  2.0
> SIGMA  10    0    0   40  2.0
>              11    0    0   40  2.0
>              12    0    0   40  2.0
>              13    0    0   40  2.0
>              14    0    0   40  2.0
>              15    0    0   40  2.0
>              16    0    0   40  2.0
>              17    0    0   40  2.0
>              18    0    0   40  2.0
>              19    0    0   40  2.0
> M            20    0    0   40  2.0
>              29    2    0   60  2.0
>              28    4    0   60  2.0
>              27    6    0   60  2.0
>              26    8    0   60  2.0
>              25   10    0   60  2.0
>              24   12    0   60  2.0
>              23   14    0   60  2.0
>              22   16    0   60  2.0
>              21   18    0   60  2.0
> K           20   20    0   60  2.0
>              19   19    0   60  2.0
>              18   18    0   60  2.0
>              17   17    0   60  2.0
>              16   16    0   60  2.0
>              15   15    0   60  2.0
>              14   14    0   60  2.0
>              13   13    0   60  2.0
>              12   12    0   60  2.0
>              11   11    0   60  2.0
> LAMBDA10   10    0   60  2.0
>               9    9    0   60  2.0
>               8    8    0   60  2.0
>               7    7    0   60  2.0
>               6    6    0   60  2.0
>               5    5    0   60  2.0
>               4    4    0   60  2.0
>               3    3    0   60  2.0
>               2    2    0   60  2.0
>               1    1    0   60  2.0
> GAMMA  0    0    0   60  2.0
>               0    0    1   20  2.0
>               0    0    2   20  2.0
>               0    0    3   20  2.0
>               0    0    4   20  2.0
> DELTA    0    0    5   20  2.0
>               0    0    6   20  2.0
>               0    0    7   20  2.0
>               0    0    8   20  2.0
>               0    0    9   20  2.0
> A            0    0   10   20  2.0
> END
>
> We renamed this hcp.klist file as case.klist_band and used it for band
> structure calculation. The calculated band structure gives the indirect
> band gap which is almost equal to the band gap obtained from SCF
> calculation.
>
> My question is, whether we can use the hcp.klist (given in Wien2k SRC
> folder) as case.klist_band for band structure calculation if the compound
> have R-3c space group and having the hexagonal lattice parameter and
> rhombohedral atomic coordinate in the case.struct file. Please let me know
> I am doing right or there is some different way to do it.
>
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