[Pw_forum] Oscillation behavior for structure optimization

ruizhi zhang rui_zhi_zhang at yahoo.com
Tue Mar 27 05:22:32 CEST 2007


hi okuno
   
  I can not slove your problem because I am a beginer as you are. But I have another way to get a monoclinic phase PZT. The input&outfile are attached below. By the way, I do not think it is correct to fix z-coordinate, because you perhaps will not get a 'groud state'.
  Hope this helps
   
  Best regards
  ruizhi

   
  INPUT:
   &control
    calculation  = 'relax'
    restart_mode = 'from_scratch'
    prefix = 'pzt.mono.rl'
    pseudo_dir   = '/'
    outdir       = '/'
 /
 &system
    ibrav=0
    celldm(1)=7.73
    nat=20
    ntyp=4
    ecutwfc=30.0
    occupations = 'fixed'
 /
 &electrons
    conv_thr = 1e-8,
    mixing_beta=0.3,
 /
 &IONS
   /
ATOMIC_SPECIES
  Pb    207.2      Pb.vdb.UPF
  Ti    47.867     Ti.vdb.UPF
  Zr    91.22      Zr.vdb.UPF
  O     15.9994    O.vdb.UPF
ATOMIC_POSITIONS
Pb      0.0     0.0     0.0
Zr      0.485   0.485   0.47
O       0.0     0.5     0.5
O       0.5     0.0     0.5
O       0.5     0.5     0.0
Pb      0.0     1.0     0.0
Ti      0.485   1.485   0.47
O       0.0     1.5     0.5
O       0.5     1.0     0.5
O       0.5     1.5     0.0
Pb      0.0     0.0     1.0
Ti      0.485   0.485   1.47
O       0.0     0.5     1.5
O       0.5     0.0     1.5
O       0.5     0.5     1.0
Pb      0.0     1.0     1.0
Zr      0.485   1.485   1.47
O       0.0     1.5     1.5
O       0.5     1.0     1.5
O       0.5     1.5     1.0
K_POINTS {automatic}
  4 2 2 0 0 0
CELL_PARAMETERS
      1  0  0
      0  2  0
      0  0  2

  OUTPUT,this is a monoclinic phase PZT
  ATOMIC_POSITIONS (alat)
Pb      -0.074746117  -0.054391084  -0.052737416
Zr       0.475968064   0.476554616   0.469572490
O       -0.002812771   0.540060157   0.546351440
O        0.538456743  -0.005360148   0.524405291
O        0.538229142   0.529414476  -0.011303199
Pb      -0.060631754   0.929474660  -0.080635128
Ti       0.461835759   1.468464184   0.467563250
O        0.029392570   1.525039365   0.520132029
O        0.532671091   1.026126063   0.530617774
O        0.531637274   1.534617711   0.026033468
Pb      -0.060631754  -0.070525340   0.919364872
Ti       0.461835759   0.468464184   1.467563250
O        0.029392570   0.525039365   1.520132029
O        0.532671091   0.026126063   1.530617774
O        0.531637274   0.534617711   1.026033468
Pb      -0.074746117   0.945608916   0.947262584
Zr       0.475968064   1.476554616   1.469572490
O       -0.002812771   1.540060157   1.546351440
O        0.538456743   0.994639852   1.524405291
O        0.538229142   1.529414476   0.988696801

   
  
yukihiro_okuno at fujifilm.co.jp wrote:
  
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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