[Pw_forum] convergence issue for energy calculation of thin film

[mohnish pandey]

Dear users,
                 I am trying to calculation energy of zinc oxide thin films
of different number of atomic layer, but the energy is not converging, I
have varied the value of beta in the range of (0.1- 0.7) , energy cutoff in
the range of (15 - 50), but the energy is not converging. I am copying my
input file for vc-relax calculation of energy of 4 atomic layer thin film.
Can anybody suggest me something for convergence.
Thanks in advance...

&control
    calculation = 'vc-relax',
    restart_mode='from_scratch',
    nstep=200,
    outdir='/home/rajpala/Desktop/wurtzite4',
    pseudo_dir='/home/rajpala/Desktop/wurtzite4'
    prefix='zno',
    tstress = .true.,
    tprnfor = .true.,
  /
  &system
    nosym =.TRUE.,ibrav=  4, a = 3.2858, c = 26,nat=  8, ntyp= 2,
    ecutwfc = 25
  /
  &electrons
   diagonalization='david'
   mixing_mode = 'plain'
   mixing_beta = 0.5
   electron_maxstep=200
   conv_thr = 1.0d-6
 /
&IONS
  ion_dynamics='bfgs'
/
 &CELL
  cell_dynamics='damp-w'
 /
ATOMIC_SPECIES
  Zn 65.390 Zn.pbe-van.UPF
  O 15.099 O.pbe-rrkjus.UPF
 ATOMIC_POSITIONS (crystal)
  Zn 0.33333333 0.66666666 0.09995
  Zn 0.33333333 0.66666666 0.2999
  Zn 0.00 0.00 0.1999
  Zn 0.00 0.00 0.40
  O  0.0 0.0 0.06899
  O  0.0 0.0 0.26885
  O  0.33333333 0.66666666 0.1689
  O  0.33333333 0.66666666 0.3689
 K_POINTS (automatic)
 4 4 1 0 0 0


-- 
Mohnish Pandey
Y6262,4th Year Undergraduate,
Department of Chemical Engineering,
IIT KANPUR
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