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I am using PAW and DFPT to carry out phonon band structure calculations for NiTi in B2 symmetry. See the attached file. The attached file shall be niti.tar. But .tar extension is not allowed (why?) and I changed its name to niti.in, which contains the DDB (combined) and the input files.

The problem is that anaddb takes for ever to compute IFC and phonon frequencies. It should generate results within a few minutes; instead, I have to use 28 cores to do such calculation (anaddb < phonon_band.files). anaddb used 35 minutes to construct the IFC, then for each q point, it took 4 minutes.

It seems to me that anaddb does not interpolate phonon frequencies (though I explicitly set ifcflag=1); instead it calculates phonons one by one using some other methods, since the computed phonon bands are not very smooth, though it looks essentially correct.

Please let me know what is wrong and how to fix it. I think it is caused by a bug in anaddb.

I solved the issue.

Should not do electric field perturbation for a metal (NiTi) at the gamma q-point.

Dear zhiwu,
Is your system metallic or insulator? I would suspect that it is metallic and thus dipdip=1 has no sense here since the electronic dielectric constant (epsilon^infty) is infinite for metals. For the same reason, using the second list of wavevector to estimate the LO/TO splitting has no meaning too. If it is the case (NiTi=metallic) then what about running your input by putting dipdip=0 and removing nph2l and qph2l?
If it is insulating, then how large is the bandgap and how big is the electronic dielectric constant?
Best wishes,
Eric