Dear developers,
I read this tutorial link http://www.fisica.uniud.it/~giannozz/QE-Tutorial/tutorial_disp.html
It mentioned that if we use ultrasoft pseudopotential, we have to use much higher ecutrho and tighter th2_ph
I have a few questions:
1. What is the reason for a higher ecutrho as well as th2_ph? Any references?
2. Do we need a high ecutrho for PAW as well?
2. I tried to calc diamond phonon dispersion and use (4 4 4) grid with C.pz-rrkjus.UPF. But I found that the phonon dispersions for ecutrho=150 and ecutrho=450 are exactly the same. Then I don't understand why the tutorial suggest such a high ecutrho as 450? Are there other criterions for a suitable ecutrho that I missed?
3. For an arbitrary ultrasoft pseudopotential, how to quickly determine a suitable ecutrho?
best regards
_______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
