[Pw_forum] convergence NOT achieved, stopping

[You Lin]

Dear pwscf developers or users:

I tried pwscf on an interface between Nickle and Alumina.
The self-consistent calculation cannot finish with the following error:

convergence NOT achieved, stopping

I found this in the manual:
--
Self-consistency is slow or does not converge.

[...] If the highest occupied and lowest unoccupied state(s) keep 
exchanging place during self-consistency, forget about reaching 
convergence. A typical sign of such behavior is that the self-consistency
error goes down, down, down, than all of a sudden up again, and so on.
Usually one can solve the problem by adding a few empty bands and a
broadening.
-- 

So I tried to manually assign more empty bands and degauss=0.0002.
I still get oscillations in total energy. The last a few total energies 
are listed below:

     total energy              = -2803.40138682 ryd
     total energy              = -2830.79824814 ryd
     total energy              = -2819.95336489 ryd
     total energy              = -2846.17498280 ryd
     total energy              = -2838.30750908 ryd
     total energy              = -2816.89515320 ryd
     total energy              = -2844.65794627 ryd
     total energy              = -2851.17678186 ryd
     total energy              = -2857.26598638 ryd
     total energy              = -2851.22021650 ryd
     total energy              = -2803.07516948 ryd
     total energy              = -2831.39193734 ryd
     total energy              = -2819.19178874 ryd
     total energy              = -2846.04973420 ryd
     total energy              = -2836.37911313 ryd
     total energy              = -2817.70612317 ryd
     total energy              = -2842.03435570 ryd
     total energy              = -2850.49039020 ryd
     total energy              = -2857.53771242 ryd
     total energy              = -2851.23397342 ryd
     total energy              = -2800.87394328 ryd
     total energy              = -2831.32149373 ryd
     total energy              = -2819.05136878 ryd

Looks like the problem still exists. I didn't finish this calculation 
since it doesn't seem to converge anyway.
Is there solution out of this problem?

More info:
I'm using espresso 3.0 running both in series and in parallel.
My input file is:
-- Start of input --
 &control
    calculation='relax'
    restart_mode='from_scratch',
    pseudo_dir = '/homes/r40/ylin/Del/Run/pwscf/espresso-3.0/pseudo/',
    outdir='/scratch1/ylin/tmp/3.0/'
    prefix='al2o3'
    tprnfor = .true., nstep=20, dt=100.
    tstress = .true., verbosity='high'
 /
 &system
    ibrav=0, celldm(1) =9.4176391165, nat=46, ntyp=3, nbnd=230,
    ecutwfc = 26, ecutrho = 288.0, nspin = 2,  
starting_magnetization(1)=0.7,
    occupations='smearing', smearing='methfessel-paxton', degauss=0.0002
 /
 &electrons
    diagonalization='david'
    conv_thr = 1.0e-2, electron_maxstep=200
    mixing_beta = 0.7
 /
 &ions
    upscale=10
 /
ATOMIC_SPECIES
 Ni 58.69 Ni.pbe-nd-rrkjus.UPF
 Al  26.98 Al.pbe-n-van_ak.UPF
 O 16.00  O.pbe-rrkjus.UPF
ATOMIC_POSITIONS {crystal}
 Ni          0.000000000          0.000000000          0.000000000
 Ni         -0.000000000         -0.000000000          0.247992113
 Ni         -0.000000000         -0.000000000          0.495984226
 Ni          0.000000000          0.500000000          0.000000000
....
  O         -0.000002801         -0.695543049          0.704618081
  O         -0.028885007         -0.333327809          0.617873620
  O          0.362212748         -1.028876505          0.617873591
  O          0.666663767         -0.637778737          0.617873627
 Al          0.333330268         -0.666660823          0.737258713
 Al          0.333330525         -0.666661167          0.845466117
CELL_PARAMETERS
          1.0000000000          0.0000000000         0.0000000000
          0.5000000000          0.8660254038         0.0000000000
          0.0000000000          0.0000000000         4.9386941745
K_POINTS automatic
 4 4 1  0 0000 0000
-- End of input --

Thanks in advance.

________________________________________

You Lin

Department of Physics
University of South Florida
4202 East Fowler Avenue
Tampa, FL 33620
________________________________________

Tel: (813)396-9220 [Office]

Homepage: http://shell.cas.usf.edu/~ylin
________________________________________