[Pw_forum] scf stops after finishing 100 iteration

[udayagiri sai babu]

Dear Dimpy Sharma
you modify your electrons card as below. i.e add the option
electron_maxstep=1000 by default it is 100. If convergence is not achieved
in 100 steps then it stops. So put the variable electron_maxstep to a high
value say 1000 so that the scf calculation runs till it is converged.

 &ELECTRONS
    diagonalization ='david'
        mixing_mode = 'plain'
           conv_thr = 1.0d-6
        mixing_beta = 0.7
        electron_maxstep=1000

On Wed, Nov 4, 2009 at 2:35 AM, Stefano de Gironcoli <degironc at sissa.it>wrote:

> have you verified that your crystal structure is reasonable using a
> visualizer like xcrysden or similar ?
> it appears to me that a couple of atoms are very very close to each other.
> stefano
>
> Dimpy Sharma wrote:
> >
> > Hi Quantum espresso users,
> >
> > I tired to perform scf calculation but it shows me the following error
> >      'convergence NOT achieved after 100 iterations: stopping'
> >
> > However the nscf calculation and projected density of states run
> > successfully, why is this so?
> >
> > My input file is as follows
> >
> > &CONTROL
> >      calculation ='scf'
> >     restart_mode = 'from_scratch'
> >           outdir = '/sfiwork/dsharma/PDOSSilane/PDOSsi/si_wfc'
> >       pseudo_dir = '/sfiwork/dsharma/QE_Pseudos/'
> >           prefix = 'si'
> >          tstress = .true.
> >          tprnfor = .true.
> >    etot_conv_thr = 1.D-4
> >    forc_conv_thr = 1.D-3
> >            nstep = 600
> >           wf_collect =.true.
> >  /
> >  &SYSTEM
> >         ibrav = 0
> >     celldm(1) =7.4088
> >           nat = 6
> >          ntyp = 1
> >       ecutwfc = 40
> >       ecutrho = 160.0
> >          nbnd = 12
> >  /
> >  &ELECTRONS
> >     diagonalization ='david'
> >         mixing_mode = 'plain'
> >            conv_thr = 1.0d-6
> >         mixing_beta = 0.7
> > /
> > &IONS
> >  /
> > &CELL
> >  cell_dynamics='none'
> >  /
> > CELL_PARAMETERS cubic
> >      1.000000000    0.000000000    0.000000000
> >      0.000000000    2.000000000    0.000000000
> >      0.000000000    0.000000000    2.000000000
> > ATOMIC_SPECIES
> >    Si   28.08600  Si.pz-vbc.UPF
> > ATOMIC_POSITIONS angstroms
> >  Si        2.95020       -0.66592       -0.12341
> >  Si        4.90939        0.61749        0.11358
> >  Si        0.99475        0.65272       -0.16138
> >  Si       -0.98472       -0.62740       -0.15123
> >  Si       -2.94624        0.68229       -0.12124
> >  Si       -4.89549       -0.61534        0.11905
> >  K_POINTS automatic
> >   4 1 1   0 0 0
> >
> > Can anybody give me any suggestions?
> >
> > Thanks
> >
> > Dimpy
> >
> > Dimpy Sharma,
> > PhD
> > Electronics Theory  Group
> > UCC,Cork
> > Ireland
> >
> >
> > ------------------------------------------------------------------------
> >
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> > Pw_forum at pwscf.org
> > http://www.democritos.it/mailman/listinfo/pw_forum
> >
>
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-- 
U.Saibabu
PhD student,
Deformation mechanisms modeling group,
Materials engineering department,
IISc Bangalore,
India.
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