[Pw_forum] Convergence issue

[Eleftheria Gkogkosi]

I have been trying to study defects in oxypnictides using QE.
Whilst it is easy to relax the pristine oxypnictide structure, the 
defective structure does not converge, i.e. convergence accuracy never 
falls under 1e-5
I have been trying:
- different smearing methods and degauss values
- increasing number of bands
- decreasing mixing beta
- different mixing modes
- different ferrum pseudopotentials
- slightly different initial ionic positions
- possibility of LDA+U

Would very much appreciate your suggestios

Quoting below the input file I use:
QUOTE

&control
  calculation='relax',
  prefix='defective supercell',
  nstep=20,
  etot_conv_thr=1.d-4,
  forc_conv_thr=1.d-3
pseudo_dir='./pseudo'
/
&system
  ibrav = 0,
  nat=24,
  ntyp=5,
  nbnd=500,
  occupations='smearing', smearing='m-v', degauss=0.011,
  ecutwfc = 80,
  !lda_plus_u=.true., Hubbard_U(4)=4.3
/
&electrons
  mixing_beta=0.3,
  conv_thr=1.d-6
  mixing_mode='local-TF'
  mixing_ndim=12
  electron_maxstep=1000
/
&ions
/
ATOMIC_SPECIES
La 138.90547 La.pbe-mt_fhi.UPF
O 15.999 O.pbe-mt.UPF !F 18.998403 F.pbe-hgh.UPF
H 1.00794 H.pbe-mt_fhi.UPF
Fe 55.845 Fe.pbe-sp-mt_gipaw.UPF !Fe.pbe-mt_fhi.UPF 
!Fe.pbe-sp-mt_gipaw.UPF
As 74.921596 As.pbe-mt_fhi.UPF

CELL_PARAMETERS angstrom
11.97     0.00     0.00
0.00     3.991600575     0.00
0.00     0.00     8.636372966

ATOMIC_POSITIONS crystal
La	0.084333	0.251	0.144227
La	0.417667	0.251	0.144227
La	0.751	0.251	0.144227
La	0.251	0.751	0.857773
La	0.584333	0.751	0.857773
La	0.917667	0.751	0.857773
O	0.251	0.251	0.001
H	0.584333	0.251	0.001
O	0.917667	0.251	0.001
O	0.084333	0.751	0.001
O	0.417667	0.751	0.001
O	0.751	0.751	0.001
Fe	0.251	0.251	0.501
Fe	0.584333	0.251	0.501
Fe	0.917667	0.251	0.501
Fe	0.084333	0.751	0.501
Fe	0.417667	0.751	0.501
Fe	0.751	0.751	0.501
As	0.084333	0.251	0.648885
As	0.417667	0.251	0.648885
As	0.751	0.251	0.648885
As	0.251	0.751	0.353115
As	0.584333	0.751	0.353115
As	0.917667	0.751	0.353115

K_POINTS automatic
1 1 1 0 0 0

UNQUOTE
-- 
Eleftheria Gkogkosi

Applied Mathematics & Physics Dept.
National Technical University of Athens
http://users.ntua.gr/elefthe