ABINIT Discussion Forums

Hello All

I have below information for its primitive cell of CaWO4 :
scalecart 2*5.2429 11.3737 angstrom
rprim
-0.5 0.5 0.5
0.5 -0.5 0.5
0.5 0.5 -0.5
ntypat 3
znucl 20 74 8
natom 12
typat 1 2 3 3 1 2 3 3 3 3 3 3
xred
5.0000000000E-01 5.0000000000E-01 0.0000000000E+00
0.0000000000E+00 0.0000000000E+00 0.0000000000E+00
2.3630000000E-01 3.2700000000E-01 3.9210000000E-01
9.3490000000E-01 8.4420000000E-01 6.0790000000E-01
2.5000000000E-01 7.5000000000E-01 5.0000000000E-01
7.5000000000E-01 2.5000000000E-01 5.0000000000E-01
7.7000000000E-02 1.8490000000E-01 5.9070000000E-01
5.9420000000E-01 4.8630000000E-01 4.0930000000E-01
5.1370000000E-01 9.2300000000E-01 1.0790000000E-01
8.1510000000E-01 4.0580000000E-01 8.9210000000E-01
6.7300000000E-01 6.5100000000E-02 9.0930000000E-01
1.5580000000E-01 7.6370000000E-01 9.0700000000E-02


After creating 2*2*2 supercell from primitive cell CaWO4( I have attached my input file.)
I have gotten below message and continue my running:
symlatt : the Bravais lattice is tI (body-centered tetragonal)
xred is defined in input file
ingeo : takes atomic coordinates from input array xred

symlatt : the Bravais lattice is tI (body-centered tetragonal)

symlatt : the Bravais lattice is tI (body-centered tetragonal)

--- !COMMENT
message: |
The Bravais lattice determined only from the primitive
vectors, bravais(1)= 4, is more symmetric
than the real one, iholohedry= 1, obtained by taking into
account the atomic positions. Start deforming the primitive vector set.
src_file: Subroutine Unknown
src_line: 0
...


symlatt : the Bravais lattice is mC (one-face-centered monoclinic)

--- !COMMENT
message: |
The Bravais lattice determined from modified primitive
vectors, bravais(1)= 2, has a lower symmetry than before,
but is still more symmetric than the real one, iholohedry= 1
obtained by taking into account the atomic positions.
src_file: Subroutine Unknown
src_line: 0
...


symlatt : the Bravais lattice is aP (primitive triclinic)
symspgr : spgroup= 1 P1 (=C1^1)

I think symmetry must not change after creating supercell. Is it correct?
How can i fix my problem?


Best regards,
Narges

Hello Narges,

In my experience, this is most likely a problem with the number of digits used for xred since the symmetry finder has a rather high precision. I suggest rebuilding your super-cell from a unit cell that contains more digits for the atomic positions (xred) with around 8 relevant decimal points.

Dear NPike,
Thank you very much. My problem is solved.
Best
Narges