[QE-users] My input dont converge

[Giuseppe Mattioli]

Dear Carlos

Remember to add your affiliation in your posts, please.

Your structure is correct. Without knowing more about your run (at  
least the code version) and your output, it is impossible to say much  
more. However, note that an "scf" (i.e., single-point) calculation is  
different from a "relax" (i.e., geometry optimization) or a "vc-relax"  
(i.e., geometry + cell parameters optimization) one. In the case of  
scf, all variables related to geometry or cell oprimizations, like the  
&ions list, but also the nstep variable in &control list, are ignored  
by the code. There is no harm in this, but the code informs you that  
there are useless parts in your input. To solve the problem you might  
try to raise a bit ecutwfc and ecutrho, as they may be poorly  
converged. As you are a new user, you should try to perform proper  
convergence tests on your pseudopotentials, and ZnO bulk can be  
considered as a nice training (I started many years ago with TiO2...).  
Finally, don't expect a good matching with the measuerd band gap (this  
may also be a possible source of instability of your calculation). In  
my hands, ZnO with PBE yields around 0.8 eV, against measured values  
of 3.0~3.4 eV, due to the double strong delocalization error affecting  
both the Zn 3d and O 2p bands.
HTH
Giuseppe


Quoting Carlos Rocha <cr490001 at gmail.com>:

> I am new to QE and its tools. I am executing an SCF calculation with pw.x
> of the hexagonal ZnO and I don´t know what's wrong with my input file
> because it don`t converge. the output said that cards /*& ions *and
> *upscale=10
> *are ignored.
>
> Input
> &control
>     calculation = 'scf',
>     restart_mode='from_scratch',
>     nstep=500
>     prefix='ZnO',
>     tprnfor = .true.
>      pseudo_dir = '/scratch/humberto/pseudos',
>      outdir='.',
> /
>  &system
>     ibrav= 4, celldm(1)= 6.2153, celldm(3)=1.6135, nat=4, ntyp= 2
>     ecutwfc =30.0,ecutrho=240.0,
> /
>  &electrons
>     electron_maxstep=200
>     mixing_mode = 'plain'
>     mixing_beta = 0.05
> /
>  &ions
>     upscale=10
> /
> ATOMIC_SPECIES
>  Zn   65.38   zn_pbe_v1.uspp.F.UPF
>  O    15.99   o_pbe_v1.2.uspp.F.UPF
> ATOMIC_POSITIONS crystal
> Zn  0.3333 0.6667  0.0005
> Zn  0.6667 0.3333  0.5005
> O   0.3333 0.6667  0.3798
> O   0.6667 0.3333  0.8798
> K_POINTS automatic
> 5 5 3 0 0 0
>
> i hope somebody can help me.



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