[Pw_forum] surface energy convergence for thin films

[mohnish pandey]

Dear users!
                    I am calculating the energy of gallium nitride thin
films of thickness of 1-10 layers. I am giving 'nstep'  equal to 200 but the
output file is not showing any  message of convergence. The program is just
completing the 200 iterations. I have played with all the parameters like
'mixing', 'smearing', etc. I am pasting the input file for 9 layer
calculation. Can anybody please point out  my mistake and get me out of it.
Sincere Thanks in advance.


 &control
    calculation = 'vc-relax',
    restart_mode='restart',
    nstep=200,
    outdir='/home/rajpala/Desktop/wurtzite9',
    pseudo_dir='/home/rajpala/Desktop/wurtzite9'
    prefix='gan',
    tstress = .true.,
    tprnfor = .true.,
  /
  &system
    nosym =.TRUE.,ibrav=  4, a = 3.1427, c = 45,nat=  18, ntyp= 2,
    ecutwfc = 25,occupations='smearing',degauss=.02,smearing='m-v'
  /
  &electrons
   diagonalization='david'
   mixing_mode = 'local-TF'
   mixing_beta = 0.1
   electron_maxstep=200
   conv_thr = 1.0d-6
 /
&IONS
  ion_dynamics='bfgs'
/
 &CELL
  cell_dynamics='damp-w'
 /
ATOMIC_SPECIES
  Ga 69.723 Ga.pbe-nsp-van.UPF
  N 14.0067 N.pbe-rrkjus.UPF
 ATOMIC_POSITIONS (crystal)
  Ga 0.33333333 0.66666666 0.0577
  Ga 0.33333333 0.66666666 0.17327
  Ga 0.00 0.00 0.1154
  Ga 0.00 0.00 0.23105
  Ga 0.33333333 0.66666666 0.288
  Ga 0.00 0.00 0.3459
  Ga 0.33333333 0.66666666 0.4045
  Ga 0.00 0.00 0.4623
  Ga 0.33333333 0.66666666 0.5206
  N  0.0 0.0 0.0398
  N  0.0 0.0 0.1553
  N  0.33333333 0.66666666 0.0957
  N  0.33333333 0.66666666 0.2130
  N  0.0 0.0 0.2708
  N  0.33333333 0.66666666 0.3279
  N  0.0 0.0 0.3873
  N  0.33333333 0.66666666 0.4443
  N  0.0 0.0 0.5035
 K_POINTS (automatic)
 6 6 1 0 0 0


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