[QE-users] problem with ph.x in calculating x-point phonon

[Lorenzo Paulatto]

> Possibly too few bands at point 746 0.00000 0.50000 0.00000 What is 
> the cause of this,
The perturbation theory used by the phonon code includes a sum over the 
partially occupied states around the Fermi energy. The code is warning 
you that there may not be enough bands over the Fermi energy for this 
sum to be properly converged. I.e. that the occupation of the higher 
band is still significantly higher than zero.
> how to solve this problem,
Increase nbnd in the input of pw.x and repeat this part of the phonon 
calculation
> will it have an impact on the final result?

The only way to know for sure, is to repeat the calculation with more bands.

hth

> Thanks and Regards Liu R F The Research Scholar, LZJTU China
>
>
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Dr. Lorenzo Paulatto
IR IMPMC - CNRS UMR 7590 / Sorbonne Université / MNHN
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