[Wien] Error in Rhombohedral (R3C) positions

[Gavin Abo]

In StructGen of w2web, why have you select spacegroup F instead of 161_R3c?

Why are you using the rhombohedral lattice parameters (a=b=c=5.63 ang, 
alpha=beta=gamma=59.99 deg) when you should be using the hexagonal ones 
(a=b=5.6291 ang, c=13.7917 ang, alpha=beta=90 deg, gamma=120 deg) 
converted with SETSTRU [http://www.cryst.ehu.es/cryst/setstru.html]?

Looking at Table 1 in Acta Materialia vol. 59 p. 4229 (2011) 
[http://dx.doi.org/10.1016/j.actamat.2011.03.047], there are three 
experimental nonequivalent rhombohedral atomic positions for BiFeO3 that 
you have to put in StructGen 
[http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg05100.html]:

Bi x=y=z=0
Fe x=y=z=0.221
O x=0.538, y=0.933,z=0.395

So why do you have 10 nonequivalent atomic positions?

On 5/27/2014 4:07 PM, mourad boujnah wrote:
> Dear users,
>
> I try to run a calculation of Rhombohedral structure for BiFeO3 with 
> R3C space group, i specify the positions of the atoms in my structure, 
>  but i find a mistake of positions "_Does not coincide with space 
> group chosen_".
> Your find below the structure of BiFeO3.
> Can some one help me Please?
>
> Best Regards
> ---------------------------------------------------------------------------------
> BiFeO3
> F LATTICE,NONEQUIV.ATOMS: 10
> MODE OF CALC=RELA unit=ang
>  10.639162 10.639162 10.639162 59.990000 59.990000 59.990000
> ATOM  -1: X=0.00000000 Y=0.00000000 Z=0.00000000
>           MULT= 1    ISPLIT= 8
> Bi         NPT=  781  R0=0.00000500 RMT=    0.1600   Z: 83.0
> LOCAL ROT MATRIX:  1.0000000 0.0000000 0.0000000
>  0.0000000 1.0000000 0.0000000
>  0.0000000 0.0000000 1.0000000
> ATOM   2: X=0.94695931 Y=0.77320530 Z=0.41586648
>           MULT= 1    ISPLIT= 8
> Bi         NPT=  781  R0=0.00000500 RMT=    0.1600   Z: 83.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   3: X=0.12806219 Y=0.25647279 Z=0.63978829
>           MULT= 1    ISPLIT= 8
> Fe         NPT=  781  R0=0.00005000 RMT=    0.1500   Z: 26.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   4: X=0.95019296 Y=0.77179058 Z=0.44385780
>           MULT= 1    ISPLIT= 0
> Fe         NPT=  781  R0=0.00005000 RMT=    0.1500   Z: 26.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   5: X=0.99520485 Y=0.67491038 Z=0.33577320
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   6: X=0.07110105 Y=0.36601829 Z=0.66778098
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   7: X=0.99021536 Y=0.68809328 Z=0.34758299
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   8: X=0.04657964 Y=0.34289224 Z=0.64963207
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM   9: X=0.24724493 Y=0.37328868 Z=0.63785978
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
> ATOM  10: X=0.97856317 Y=0.66464945 Z=0.32036458
>           MULT= 1    ISPLIT= 0
> O          NPT=  781  R0=0.00010000 RMT=    0.1000   Z:  8.0
> LOCAL ROT MATRIX:  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>  0.0000000 0.0000000 0.0000000
>    0      NUMBER OF SYMMETRY OPERATIONS
>
>
> -- 
> Mourad BOUJNAH
> PhD Student in laboratory of magnetism and physics of high energy
> Faculty of Sciences in Rabat - Morocco
> Tel: _+212 __677316706_
> Email: _boujnah.mourad at gmail.com <mailto:boujnah.mourad at gmail.com>
> _/"Research is to see what everybody else has seen, and to think what 
> nobody else has thought"/

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