17.  Do this for each irrep. You will find the following frequencies (given below approximately):

irrep1 (       point):  341 cm-1 (3 times); the other 3 modes have zero frequencies, they correspond to the translations of the crystal as a whole

irrep2 (   X point):  267.6 cm-1 (2 times); 344 cm-1; 411.9 cm-1 (2 times) and 546.5 cm-1

As expected, the three irreps 2, 3 and 4 give identical results (they correspond to the same point X in the Brillouin zone).

18.  We can work out the contribution of all frequencies of any irrep into the vibrational free energy via option Fr, below:

The number of temperature points and the temperature range are set using options Np and Tr, respectively. 

19.  Finally, one can create a movie.xyz file with the option Vs which, if played on any of the visualisation software (e.g. using xmakemol), would show how atoms oscillate due to a particular normal mode. The oscillation amplitude is set via option Da.

irrep3 (   X point):  267.6 cm-1 (2 times); 344 cm-1; 411.9 cm-1 (2 times) and 546.5 cm-1

irrep4 (   X point):  267.6 cm-1 (2 times); 344 cm-1; 411.9 cm-1 (2 times) and 546.5 cm-1

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