Dear Top Gun,
For the H at wyckoff site 4d you need to give 1/3 and 2/3 in higher precision, otherwise the rounding of error will give 12 sites that are extremely close by since Elk uses a smaller criterion for when they are equivalent .
Good luck!
Lars
Nb: the 0.33333 for the Y site might seemingly be 1/3, but it is in fact a free parameter of the 6f wyckoff position ...
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
this is not related to the earlier problem you had with accuracy,
In fact this result it is not even in error.
Unfortunately the international crystallograhic association long ago decided that the Wyckoff multiplicity is referred to the conventional cell not the primitive.
Elk will use the primitive and since the concentional cell is four times larger than the primitive, the site 4a has only one site per (primitive) cell ...
Sincerely,
Lars
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Dear Lars,
It means 4a (0.0 0.0 0.0) will show only eight atoms on the eight corners of unit cell and would not show six atoms at the six faces of unit cell. how will it be visualised and compared with some reference structure available.
ssingh
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
It seems to be a mix up of conventional cell which is face centered cubic and primitive cell that is cubic. I have no idea why ... Maybe you can send me the GEOMETRY.OUT you try to plot?
In general, at Bilbao web-page you can see the Wyckoff positions of Space group #225
at the top you can read beneath Coordinates the four face centering vectors which bring you from primitive to conventional site. Non-trivial "Coordinates" indicate that they use multiplicity for a conventional site and not for primitive cell. For instance compare with the corresponding space group #222, which is primitive.
Dear all,
This spacegroup file is not giving right geometry.out. it is showing 32 atoms instead of 24.
11.96197 11.96197 12.4722 : a,b,c
90.0 90.0 120.0 : bc ,ac ,ab
1 1 1 : ncell
.true : primcell
2 : nspecies
'A' : spsymb
1 : nwpos
0.33333 0.00000 0.25000 : wpos
'B'
3
0.35600 0.32800 0.09600
0.33333 0.66667 0.16700
0.00000 0.00000 0.25000
S Singh
Last edit: TOP GUN 2022-01-06
Dear Top Gun,
For the H at wyckoff site 4d you need to give 1/3 and 2/3 in higher precision, otherwise the rounding of error will give 12 sites that are extremely close by since Elk uses a smaller criterion for when they are equivalent .
Good luck!
Lars
Nb: the 0.33333 for the Y site might seemingly be 1/3, but it is in fact a free parameter of the 6f wyckoff position ...
Dear Lars,
The following Wycoff coordinate is generating only one atomic position, whereas it should generate 4. (it is 4a for Fm-3m)
'A' : spsymb
1 : nwpos
0.000000 0.000000 0.000000 : wpos
ssingh
Last edit: TOP GUN 2022-05-29
Dear topgun,
this is not related to the earlier problem you had with accuracy,
In fact this result it is not even in error.
Unfortunately the international crystallograhic association long ago decided that the Wyckoff multiplicity is referred to the conventional cell not the primitive.
Elk will use the primitive and since the concentional cell is four times larger than the primitive, the site 4a has only one site per (primitive) cell ...
Sincerely,
Lars
Dear Lars,
It means 4a (0.0 0.0 0.0) will show only eight atoms on the eight corners of unit cell and would not show six atoms at the six faces of unit cell. how will it be visualised and compared with some reference structure available.
ssingh
Thanks.
Dear Ssingh,
It seems to be a mix up of conventional cell which is face centered cubic and primitive cell that is cubic. I have no idea why ... Maybe you can send me the GEOMETRY.OUT you try to plot?
In general, at Bilbao web-page you can see the Wyckoff positions of Space group #225
at the top you can read beneath Coordinates the four face centering vectors which bring you from primitive to conventional site. Non-trivial "Coordinates" indicate that they use multiplicity for a conventional site and not for primitive cell. For instance compare with the corresponding space group #222, which is primitive.
Best wishes,
Lars
dear lars,
How can I get the right structure which can be compared with the available structure on crystal data repository websites.
ssingh