displacement of atoms

[bmalvandi]

hello
I calculated the ohonon frequencies for LaCoO3 and I displaced only 1 atom of 5 atoms in a cell
I want to know according to my output is it enough to displace only 1 atom, or I must displace more?
thanks


0.0 0.0 0.0
1/2 1/2 1/2
0.502 0.5 0.0
0.5 0.0 0.5
0.0 0.5 0.5

and the output:


Phonon wavevector (reduced coordinates) : 0.00000 0.00000 0.00000
Phonon energies in Hartree :
0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00
0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 7.972934E-04
7.972934E-04 7.972934E-04 2.717973E-03 2.717973E-03 2.717973E-03
Phonon frequencies in cm-1 :
- 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00
- 0.000000E+00 0.000000E+00 0.000000E+00 0.000000E+00 1.749857E+02
- 1.749857E+02 1.749857E+02 5.965261E+02 5.965261E+02 5.965261E+02
chkph3 : WARNING -
The dynamical matrix was incomplete : phonon frequencies may be wrong ...

[gonze]

Dear BMalvandi,

In order to get the phonon frequencies of cubic LaCoO3, you are NOT supposed
to move the atoms by hand, be it one or more. You should
simply define the set of perturbations, using rfatpol and rfdir.
Please, read carefully the tutorials, and also see the examples input files
in the ABINIT package, especially in the tests/v2 subdirectory .

Best wishes,
X