[Pw_forum] some trouble in Phonon dispersion calculation

[Wenxiaodong]

Dear everybody
  Recently, I did a phonon dispersion calculation using PWscf. However, I can not obtain smooth phonon dispersion. That is to say, the phonon dispersion looks like zigzag shape. For making sure, I tried to use the example 07 (in PWscf), while there are same phenomena for phonon dispersion. By the way, I used the plotband.x to handle data.
  If you have some experience about this, could you tell me the reasons? I will very very appreciate you!
Best
Xiaodong