[Pw_forum] problem with symmetry recognition

[pascal boulet]

Dear all,

I am struggling to make QE recognize the symmetry of a solid compound.
The group number is 116, it is a tetragonal primitive structure with 9
atoms in the primitive unit cell.
 

In the input file I give the reduced coordinates I obtained from the
Pearson database. I tried the following structure descriptions:

alat  = 1.,  ibrav = 0
CELL_PARAMETERS cubic
10.461 0. 0.
0. 10.461 0.
0. 0. 33.172

then:
celldm(1)=10.461, celldm(3)=3.171, ibrav=6

No way!

The idea is to optimize the cell parameters, so I would like QE to
retain the crystal symmetry.

Does anybody have an idea what could be wrong?

Thank you
Pascal


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