[Pw_forum] scf_must_converge

[Ari P Seitsonen]

Dear Florence,

   I would try different values of 'mixing_beta' in the namelist 
'electrons'; typically in such transition metal systems I use values 
0.1-0.3.

     Greetings from Sunny Zurich,

        apsi

PS I often use values 1e-8 or similar in metallic systems. Please notice 
that the suitable value for 'degauss' depends also on the algorithm to 
used: I use the value '0.0036749326', but with Fermi-Dirac broadening; a 
similar value with Gaussian broadening is indeed quite different

-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
   Ari P Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
   Physikalisch-Chemisches Institut der Universitaet Zuerich
   Tel: +41 44 63 54 497  /  Mobile: +41 79 71 90 935


On Fri, 2 Nov 2012, Bramha Pandey wrote:

> 
> On Fri, Nov 2, 2012 at 3:09 PM, florence liu <florenceliu86 at gmail.com>
> wrote:
>       Dear Davide, Dear Bramha,
>  
> thankyou for your answers.
> i am only optimizing atomic positions of a Pt surface with vdw-DF
> funtionals,.... so nothing too special, i guess.
>  
> as you suggested, here is the complete input file:
>  
>  
>  &control
>     prefix='Ptsurface47',
>     pseudo_dir= '(...)',
>     outdir = '(...)',
>     calculation='scf',
> 
> As per your problem you want to optimize, so set 'relax' or 'vc-relax' in
> calculation field.
>           forc_conv_thr=0.000389,
>           tefield=.TRUE.,
>           dipfield=.TRUE.,
>        /
>        &system
>           ibrav=  0,  nat=  16, ntyp= 1,
>           ecutwfc = 47, occupations='smearing', smearing='gaussian',
>           degauss= 0.00367487
> 
> it seems very low value to me. set it as a 0.02 or 0.01. and apply what i am
> already said before.
>           edir=3,
>           emaxpos=0.6,
>           eopreg=0.1,
>           input_dft='sla+pw+rpb+vdw1'
>        /
>        &electrons
>        electron_maxstep=100,
>        conv_thr=7.35D-8,
>        scf_must_converge=.false. 
>        /
>  &ions
>  /
>  &cell
>  /
> CELL_PARAMETERS (angstrom)
> 5.7210401300000000    0.0000000000000000    0.0000000000000000
> 2.8605200700000000    4.9545660900000000    0.0000000000000000
> 0.0000000000000000    0.0000000000000000   22.9590000000000000
> ATOMIC_SPECIES
>  Pt  196.966   Pt.revPBE-n-kjpaw.UPF
> ATOMIC_POSITIONS (crystal)
> Pt  0.0000000000000000  0.0000000000000000  0.3051881400000000 1 1 1
> Pt  0.5000000000000000  0.0000000000000000  0.3051881400000000 1 1 1
> Pt  0.0000000000000000  0.5000000000000000  0.3051881400000000 1 1 1
> Pt  0.5000000000000000  0.5000000000000000  0.3051881400000000 1 1 1
> Pt  0.3333333333333333  0.3333333333333333  0.2034587900000000 1 1 1
> Pt  0.8333333333333333  0.3333333333333333  0.2034587900000000 1 1 1
> Pt  0.3333333333333333  0.8333333333333333  0.2034587900000000 1 1 1
> Pt  0.8333333333333333  0.8333333333333333  0.2034587900000000 1 1 1
> Pt  0.1666666666666666  0.1666666666666666  0.1017293800000000 0 0 0
> Pt  0.6666666666666666  0.1666666666666666  0.1017293800000000 0 0 0
> Pt  0.1666666666666666  0.6666666666666666  0.1017293800000000 0 0 0
> Pt  0.6666666666666666  0.6666666666666666  0.1017293800000000 0 0 0
> Pt  0.0000000000000000  0.0000000000000000  0.0000000000000000 0 0 0
> Pt  0.5000000000000000  0.0000000000000000  0.0000000000000000 0 0 0
> Pt  0.0000000000000000  0.5000000000000000  0.0000000000000000 0 0 0
> Pt  0.5000000000000000  0.5000000000000000  0.0000000000000000 0 0 0
> 
> K_POINTS (automatic)
> 5 5 1 0 0 0
>