[Pw_forum] convergence problem in scf calculation in rare earth oxide Sm2O3

[Mohammed Khalafalla]

Dear all,
I could not achieve scf convergence in Sm2La2O6 (the input file is attached
herewith). This was the case even after several 'restart' of the
calculation with different pseudpotentials specially for 'O' atom. I guess
I used well tested PAW psedu for rare earth from
http://www.vlab.msi.umn.edu/resources/repaw/index.shtml
I used recommended hubbard potentials and spin polarization, but no change.
Generally I found convergence in (Sm,O) system to be difficult. Can you
kindly let me know which parameter set-up would determine successful
convergence in (Sm,O) system?
Regards,
Mohammed A. H. Khalafalla (PhD)
Taibah University
KSA
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&control
   calculation = 'relax' ,
  restart_mode='restart',
   prefix = 'pwscf' ,
   outdir = './tmp2' ,
   pseudo_dir = '/home/mahk/Programs/qe-6.2/pseudo' ,
   disk_io = 'high' ,
   etot_conv_thr = 1.0d-8 ,
   forc_conv_thr = 1.0d-3 ,
   verbosity='high'
/
&system
   ibrav = 0 ,
   celldm(1) = 1.889725989 ,
   ecutwfc = 60 ,
!   ecutrho =  ,
   occupations = 'smearing' ,
   nspin=2
   starting_magnetization(1)=1,
   starting_magnetization(2)=1,
   smearing = 'mv' ,
   degauss = 0.2 ,
  ! nosym=.true.
   lda_plus_u=.TRUE.,
   lda_plus_u_kind=0,
   Hubbard_U(1)=9.0,
   Hubbard_U(2)=3.3,
   nat = 10 , 
   ntyp = 3 , 
/
&electrons
   conv_thr = 1.0d-8 ,
   diagonalization = 'david' ,
   mixing_mode = 'plain' ,
   startingpot = 'atomic' ,
   startingwfc = 'atomic+random' ,
   mixing_beta = 0.2 ,
/
&ions
   ion_dynamics = 'bfgs' ,
/
&cell
   cell_dynamics = 'bfgs' ,
   cell_factor = 2.0 ,
   press = 0.0 ,
   press_conv_thr = 1.0d-3 ,
/
CELL_PARAMETERS alat
1.897050000 -3.285787000 0.000000000
0.000000000 0.000000000 -6.011400000
5.691150000 3.285787000 0.000000000
ATOMIC_SPECIES
La   138.905 La.GGA-PBE-paw-v1.0.UPF
Sm   150.36  Sm.GGA-PBE-paw-v1.0.UPF
O    15.9994 O.pbe-n-kjpaw_psl.0.1.UPF
! O    15.9994 O.pbe-kjpaw.UPF
! O    15.9994 O.pbe-hgh.UPF
ATOMIC_POSITIONS angstrom
  Sm 5.691339705 1.095152807 -1.497439740
  La 3.794289705 -2.190634193 -1.497439740
  La 1.897239705 -1.095152807 -4.513960260
  Sm 5.691339705 -1.095152807 -4.513960260
  O 7.588200000 0.000000000 -6.011400000
  O 3.794100000 0.000000000 -6.011400000
  O 1.896860295 -1.095152807 -2.134648140
  O 5.690960295 -1.095152807 -2.134648140
  O 3.793910295 -2.190634193 -3.876751860
  O 5.690960295 1.095152807 -3.876751860
K_POINTS automatic
   3 5 3 0 0 0