warning The dynamical matrix was incomplete

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mverstra
Posts: 655
Joined: Wed Aug 19, 2009 12:01 pm

warning The dynamical matrix was incomplete

Post by mverstra » Tue Jun 22, 2010 4:04 pm

Hello ABINIT users

I am getting the following warning in phonon calculations:
The dynamical matrix was incomplete : phonon frequencies may be wrong
Does anyone knows what is wrong and how can I fix it?
Thanks in advance.

Best regards,Payam Norouzzadeh



Hello,

this warning is given by abinit but is not a problem: when you calculate certain perturbations at a given q-point abinit tries to immediately complete and diagonalize the dynamical matrix. In general this is not possible, as you have not done a full set of irreducible perturbations all at once (hence the warning). The frequencies are output, but many may be 0 because certain dynamical matrices have not been calculated yet.

You need to continue the calculations and use mrgddb to merge the DDB files, and then anaddb to do the reconstruction of the dynamical matrix. Follow out the whole of the rf tutorials and you will see the phonon frequencies will come out when anaddb is run.
Matthieu Verstraete
University of Liege, Belgium

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