Hello,

I am new to this topic. I used ZG calculations to include anharmonicity for phonon frequencies, and the system is a polar insulating material (SrTiO3). I took this as a test sample to learn the ZG calculations. I successfully calculated phonon frequencies.

Now my question is:

1. How do i calculate phonon linewidths from this moment on, since we have already calculated force constants where full anharmonic effects are incorporated?

Phono3py uses the same procedure, but there is one thing it needs .yaml file to gather all the force constants (ZG calculations do not provide that). Moreover, Phono3py only uses 3rd order effects, not full anharmonic effects.

2. Could you suggest, at this moment, which calculation i must take?

If I choose something such as EPW calculation, then it is for electron-phonon coupling (it is probably made for all materials), but would it be okay to pursue ? In that case i need to start over again after ph.x calculations, and for a big system it will cost almost double time ?

I look forward to your response on this.

Best wishes,

Achintya

University of Manchester

## Phonon linewidth calculation after ZG

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