Dynamic matrix calculation gave me all 0 frequencies, can't figure out why

[hanc0129]

I have tried to carry out a dynamic matrix calculation of a simple carbon monoxide molecule (CO), in an attempt to figure out its zero point energy (ZPE). I have carried out many attempts but the frequencies I got from using dymmatrix.pl were always all 0. It's the first time I'm doing a dynamic matrix calculation so can you tell me where went wrong in my code? I'm attaching the INCAR, POSCAR, DISPLACECAR and the OUTCAR that comes after the calculation. The molecular geometry was already optimized in the POSCAR file.

Thank you!

[graeme]

You need to set ICHAIN=1 to use our dynamical matrix code.

There are additional instructions here: http://theory.cm.utexas.edu/vtsttools/dymmat.html

[hanc0129]

Hi. I have changed value of ICHAIN from 0 to 1. But the calculation still gives me all 0 frequencies. Are there additional problems with my code? Should the atoms in POSCAR all set to "T" or "F" for this to work?

Many thanks

[graeme]

Ah, good point, yes, set the atomic degrees of freedom to T and change the sign of your EDIFFG. With everything frozen the force will be precisely zero and the run will stop after one iteration.