[QE-users] NON CONVERGENCE OF PHONON CALCULATION DUE TO LIMITED NUMBER OF ITERATIONSR

[Giuseppe Mattioli]

On top of this:

1) Did you relax your system with pw.x (calculation='relax')? In order  
to have meaningful frequencies and smooth convergence with DFPT you  
should stay very close to the energy minimum.

2) ecutwfc = 60.0

It might be too low for your norm-conserving B pseudopotential. Have  
you tested the convergence of pw.x results wrt the basis set?

3) ecutrho = 600,

It is useless with NC PPs. The code should automatically assign  
ecutrho=4*ecutwfc. Check it in the pw.x output.

HTH
Giuseppe

Quoting Christoph Wolf <wolf.christoph at qns.science>:

> At first glance your system is 2-dimensional but you sample out-of plane
> for ph.in (q3=3).
>
> try an appropriate q-mesh such as 3x3x1, 5x5x1, ... You can see that the
> convergence problem occurs at a q-point that is out of plane:
>
>                   q = (   0.0000000   0.0000000   0.1059000 )
>
> HTH,
>
> Chris
>
>
> --
> Postdoctoral Researcher
> Center for Quantum Nanoscience, Institute for Basic Science
> Ewha Womans University, Seoul, South Korea



GIUSEPPE MATTIOLI
CNR - ISTITUTO DI STRUTTURA DELLA MATERIA
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E-mail: <giuseppe.mattioli at ism.cnr.it>