supercell tetragonal distortion

[lsam]

Dear all,

We are trying to calculate the elastic onstants for TiN using a 8 atoms supercell . We applied a tetragonal distortion to the supercell and VASP found a body centered tetragonal cell when was expected a face centered tetragonal cell.

POSCAR:

(Ti N)4
1.00000000000000
4.28262 0.0000000000000000 0.0000000000000000
0.0000000000000000 4.28262 0.0000000000000000
0.0000000000000000 0.0000000000000000 4.2187
4 4
Direct
0.0000000000000000 0.0000000000000000 0.0000000000000000
0.0000000000000000 0.5000000000000000 0.5000000000000000
0.5000000000000000 0.0000000000000000 0.5000000000000000
0.5000000000000000 0.5000000000000000 0.0000000000000000
0.5000000000000000 0.5000000000000000 0.5000000000000000
0.5000000000000000 0.0000000000000000 0.0000000000000000
0.0000000000000000 0.5000000000000000 0.0000000000000000
0.0000000000000000 0.0000000000000000 0.5000000000000000

Do you know what I am doing wrong?

Regards

[admin]

there is nothing wrong with your input, the symmetry analysis obviously rotates the cell such that it is reduced to a bct cell.
The LATTYP: found .... line has no effect on the remaining calculation, the cell is of course taken from POSCAR (fct)