[Pw_forum] Oscillation behavior for structure optimization

[yukihiro_okuno at fujifilm.co.jp]

Dear PWscf Users.

I'm now calculating the structure optimization for
monoclinic structure of PZT ( put a little shere stress for
tetragonal structure).

But the calculation is not conversed and the Total force
is oscillate like below, and this does not happen for tetragonal case.)

 Total force =     0.029288     Total SCF correction =     0.000028
     Total force =     0.610879     Total SCF correction =     0.000006
     Total force =     0.031826     Total SCF correction =     0.000017
     Total force =     0.017717     Total SCF correction =     0.000010
     Total force =     0.006548     Total SCF correction =     0.000009
     Total force =     0.004523     Total SCF correction =     0.000024
     Total force =     0.002241     Total SCF correction =     0.000004
     Total force =     0.001565     Total SCF correction =     0.000008
     Total force =     0.001102     Total SCF correction =     0.000005
     Total force =     0.001312     Total SCF correction =     0.000010
     Total force =     0.001605     Total SCF correction =     0.000009
     Total force =     0.001865     Total SCF correction =     0.000006
     Total force =     0.002391     Total SCF correction =     0.000005
     Total force =     0.002574     Total SCF correction =     0.000005
     Total force =     0.001872     Total SCF correction =     0.000008
     Total force =     0.001495     Total SCF correction =     0.000006
     Total force =     0.001430     Total SCF correction =     0.000005
     Total force =     0.001529     Total SCF correction =     0.000003
     Total force =     0.001736     Total SCF correction =     0.000004
     Total force =     0.002315     Total SCF correction =     0.000004
     Total force =     0.002271     Total SCF correction =     0.000008
     Total force =     0.001826     Total SCF correction =     0.000008
     Total force =     0.001623     Total SCF correction =     0.000004
     Total force =     0.001605     Total SCF correction =     0.000007
     Total force =     0.001720     Total SCF correction =     0.000006
     Total force =     0.002129     Total SCF correction =     0.000003
     Total force =     0.002290     Total SCF correction =     0.000007
     Total force =     0.002437     Total SCF correction =     0.000006
     Total force =     0.002619     Total SCF correction =     0.000006
     Total force =     0.002860     Total SCF correction =     0.000007
     Total force =     0.003199     Total SCF correction =     0.000006
     Total force =     0.003772     Total SCF correction =     0.000006


My input file is like below and how should we treat such a trouble?

 &control
    calculation  = 'relax',
    restart_mode = 'from_scratch',
    pseudo_dir   = '/home/okuno/PWSCF/espresso-3.2/pseudo/',
    outdir       = './',
    prefix='PZT'
    forc_conv_thr = 1.0D-4
 /
 &system
    ibrav=12
    celldm(1)=7.57696068724
    celldm(2)=2.09
    celldm(3)=1.00
    celldm(4)=0.00499993750117
    nat=10
    ntyp=4
    nbnd=44
    ecutwfc=60.0
    ecutrho = 600.0
    occupations = 'fixed'
    degauss=0.00
 /
 &electrons
    conv_thr = 1e-10,
    mixing_beta=0.3,
 /
&IONS
 ion_dynamics='bfgs'
 bfgs_ndim=3
 pot_extrapolation = "second_order"
 wfc_extrapolation = "second_order"
 trust_radius_min=1.0D-4
/
ATOMIC_SPECIES
  Pb  207.2     pb_ps.uspp.UPF
  Zr  91.224    zr_ps.uspp.UPF
  Ti  47.867    ti_ps.uspp.UPF
  O   15.9994   o_ps.uspp.UPF
ATOMIC_POSITIONS {crystal}
Pb 0.0 0.00000 0.0 1 1 0
Pb 0.0 0.53106 0.0 1 1 0
Zr 0.5 0.24462 0.5 1 1 0
Ti 0.5 0.74062 0.5 1 1 0
O  0.5 0.95432 0.5 1 1 0
O  0.5 0.48072 0.5 1 1 0
O  0.5 0.19090 0.0 1 1 0
O  0.0 0.19090 0.5 1 1 0
O  0.5 0.71336 0.0 1 1 0
O  0.0 0.71336 0.5 1 1 0
K_POINTS {automatic}
  6 6 6 0 0 0







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