[Pw_forum] Slow convergence of Fe-111 surface by QE

[Narendranath Ghosh]

Dear all!

I am currently trying to optimize a Fe-111 surface.But I find very slow
convergence even after 229 iteration it didn't get converged.I have changed
some parameters like smearing , degauss ,nspin, K_POINTS but nothing
happened.
*Input*
 &CONTROL
  calculation='relax',
  outdir='/share_home/hpc/BONS_QE/Fe-111/OUTPUT',
  prefix='Fe-111',
  pseudo_dir='/share_home/hpc/BONS_QE/pseudo',
  verbosity='low',
  nstep=500,
/

&SYSTEM
  ibrav=0,
  celldm(1)=22.9819600668d0,
  nat=81,
  ntyp=1,
  ecutwfc=30.0d0,
  input_dft='PBE',
  nosym = .true.,
  occupations='smearing',
  smearing='mv',
  degauss=0.005000d0,
  starting_magnetization(1)=0.5


/

&ELECTRONS
  mixing_mode='local-TF',
  mixing_beta=0.700d0,
  electron_maxstep=500,
/

&IONS
/

ATOMIC_SPECIES
  Fe 55.845000d0 Fe.pbe-mt_fhi.UPF

ATOMIC_POSITIONS {alat}
Fe       0.166666360   0.096224929   1.432718760
Fe       0.499999991   0.096224958   1.432718812
Fe       0.833333491   0.096224719   1.432718553
....................................................................

K_POINTS {automatic}
3 3 1 0 0 0
CELL_PARAMETERS {alat}
  1.000000000000d0  0.000000000000d0  0.000000000000d0
  -0.500000000000d0  0.866025403784d0  0.000000000000d0
  0.000000000000d0  0.000000000000d0  3.339792528637d0


*Output*

iteration #227     ecut=    30.00 Ry     beta=0.70

     Davidson diagonalization with overlap

     ethr =  3.21E-08,  avg # of iterations =  1.0



     total cpu time spent up to now is   135955.8 secs



     total energy              =   -2984.09846782 Ry

     Harris-Foulkes estimate   =   -2984.09846943 Ry

     estimated scf accuracy    <       0.00017650 Ry



     iteration #228     ecut=    30.00 Ry     beta=0.70

     Davidson diagonalization with overlap

     ethr =  2.72E-08,  avg # of iterations =  1.0



     total cpu time spent up to now is   136477.9 secs



     total energy              =   -2984.09846204 Ry

     Harris-Foulkes estimate   =   -2984.09847440 Ry

     estimated scf accuracy    <       0.00049769 Ry



     iteration #229     ecut=    30.00 Ry     beta=0.70

     Davidson diagonalization with overlap

     ethr =  2.72E-08,  avg # of iterations =  1.0



     total cpu time spent up to now is   137011.1 secs



     total energy              =   -2984.09846816 Ry

     Harris-Foulkes estimate   =   -2984.09847046 Ry

     estimated scf accuracy    <       0.00020624 Ry

Any comment to help me getting started is very much appreciated!



Best regards,

Naren







*Dr. Narendra Nath Ghosh*

*Research Associate*

*University of Gour Banga*

*Department of Chemistry*

*Malda-732102*

*India*

*Phone: +919126667601*
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