ABINIT Discussion Forums

Hello,
thank you for your previous answer,i have fonud wyckoff bifeo3 in papers.i have three wyckoff and plot bifeo3 with them but i don't know how to find xred?what is your suggest?please answer me?
thankyou verry much.

Hello Mina,

I have the impression to have answered this one already. Anyway ... download http://www.crystallography.net/cif/1/1001090.cif i.e. the cif file for your molecule.
Look at the end of the file ...

Bi1 Bi3+ 6 a 0. 0. 0. 1. 0 d
Fe1 Fe3+ 6 a 0. 0. 0.2212(15) 1. 0 d
O1 O2- 18 b 0.443(2) 0.012(4) 0.9543(20) 1. 0 d

Reduced coordinated are there, ready to copied in Abinit input file under xred i.e. for Bi 0 0 0, for Fe 0 0 0.2212 and for O 0.443 0.012 0.9542. Get the spacegroup from the beginning of the same file, give it to spgroup variable; look for cell_length values give them to acell (units!); look for cell_angle values and give them to angdeg ... and you have your unit cell .
For a short theory introduction, look at http://en.wikipedia.org/wiki/Fractional_coordinates

Kind regards,

Alain

Hello Alain,
thankyou for your guid,i did that but i have 'WARNING' and 'ERROR' like this.
please answer me and guide me what is the roote of my mistake?
thankyou verry much.
Trouble finding symmetrically equivalent atoms
Applying inv of symm number 5 to atom number 2 of typat 2
gives tratom= -1.2326E-32 -1.2326E-32 -2.7880E-01.
This is further away from every atom in crystal than the allowed tolerance.
The inverse symmetry matrix is -1 0 0
1 1 0
uble finding symmetrically equivalent atoms
Applying inv of symm number 2 to atom number 3 of typat 3
gives tratom= -1.2000E-02 4.3100E-01 9.5420E-01.
This is further away from every atom in crystal than the allowed tolerance.
The inverse symmetry matrix is 0 1 0
-1 -1 0
0 0 1
and the nonsymmorphic transl. tnons = 0.0000000 0.0000000 0.0000000
The nearest coordinate differs by -4.550E-01 4.190E-01 0.000E+00
for indsym(nearest atom)= 3

This indicates that when symatm attempts to find atoms symmetrically
related to a given atom, the nearest candidate is further away than some
tolerance. Should check atomic coordinates and symmetry group input data.
symatm : ERROR -
Largest error (above) is so large (0.01) that either input atomic coordinates (xred)
are wrong or space group symmetry data is wrong.
Action : correct your input file.