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I have been trying to optimize the geometry of a copper based metal halide perovskite. I opened the CIF file using BURAI GUI and generated the VC-RELAX input file.

I have increased the steps to be 200 but it's not converging either. Should I increase it more or making converging not necessary, or change the geometry? I'm using 222 geometry

&CONTROL
calculation   = "vc-relax"
etot_conv_thr =  1.48000e-03
forc_conv_thr =  1.00000e-04
max_seconds   =  1.72800e+05
nstep         = 100
outdir        = "./out/"
prefix        = "aiida"
pseudo_dir    = "./pseudo/"
tprnfor       = .TRUE.
tstress       = .TRUE.
verbosity     = "high"
/

&SYSTEM
a                         =  1.11000e+01
b                         =  1.11100e+01
c                         =  2.73500e+01
cosab                     = -4.97428e-01
cosac                     = -2.02275e-01
cosbc                     = -1.04720e-03
degauss                   =  1.00000e-02
ecutrho                   =  2.25000e+02
ecutwfc                   =  2.50000e+01
ibrav                     = 14
nat                       = 148
nosym                     = .FALSE.
nspin                     = 2
ntyp                      = 6
occupations               = "smearing"
smearing                  = "gaussian"
starting_magnetization(1) =  2.00000e-01
starting_magnetization(2) =  0.00000e+00
starting_magnetization(3) =  0.00000e+00
starting_magnetization(4) =  0.00000e+00
starting_magnetization(5) =  0.00000e+00
/

&ELECTRONS
conv_thr         =  1.00000e-06
electron_maxstep = 200
mixing_beta      =  4.00000e-01
startingpot      = "atomic"
startingwfc      = "atomic+random"
/

&IONS
ion_dynamics = "bfgs"
/

&CELL
cell_dynamics  = "bfgs"
/

K_POINTS {automatic}
 2  2  2  0 0 0

ATOMIC_SPECIES
C      12.01070  C.pbesol-n-kjpaw_psl.1.0.0.UPF
Cl     35.45300  cl_pbesol_v1.4.uspp.F.UPF
Cu     63.54600  Cu.paw.z_11.ld1.psl.v1.0.0-low.upf
H       1.00794  H.pbesol-rrkjus_psl.1.0.0.UPF
N      14.00670  N.pbesol-theos.UPF
O      15.99940  O.pbesol-n-kjpaw_psl.0.1.UPF

ATOMIC_POSITIONS {crystal}
Cu      0.893200   0.446600   0.339890
Cu      0.106800   0.553400   0.660110
Cu      0.664500   0.413800   0.244840
Cu      0.335500   0.586200   0.755160
Cu      0.993800   0.580400   0.244720
Cu      0.006200   0.419600   0.755280
Cu      0.831000   0.250700   0.244780
Cu      0.169000   0.749300   0.755220
Cl      0.949000   0.474600   0.424110
Cl      0.051000   0.525400   0.575890
Cl      0.643300   0.386000   0.328930
Cl      0.356700   0.614000   0.671070
Cl      0.942400   0.256500   0.329040
Cl      0.057600   0.743500   0.670960
Cl      0.072100   0.685500   0.328940
Cl      0.927900   0.314500   0.671060
Cl      0.585900   0.165600   0.205400
Cl      0.414100   0.834400   0.794600
Cl      0.785700   0.619200   0.205400
Cl      0.214300   0.380800   0.794600
Cl      0.038700   0.419500   0.205100
Cl      0.961300   0.580500   0.794900
Cl      0.171800   0.771700   0.221000
Cl      0.828200   0.228300   0.779000
Cl      0.822000   0.049000   0.221700
Cl      0.178000   0.951000   0.778300
Cl      0.451500   0.401100   0.221500
Cl      0.548500   0.598900   0.778500
Cl      0.845100   0.424000   0.269000
Cl      0.154900   0.576000   0.731000
O       0.554300   0.972700   0.398700
O       0.445700   0.027300   0.601300
O       0.816500   0.844600   0.398100
O       0.183500   0.155400   0.601900
O       0.454700   0.692800   0.505600
O       0.545300   0.307200   0.494400
O       0.743600   0.050600   0.505500
O       0.256400   0.949400   0.494500
O       0.426400   0.582100   0.398400
O       0.573600   0.417900   0.601600
O       0.811300   0.762300   0.505100
O       0.188700   0.237700   0.494900
N       0.714600   0.857000   0.570600
N       0.285400   0.143000   0.429400
N       0.553900   0.776800   0.331000
N       0.446100   0.223200   0.669000
H       0.689440   0.844829   0.533761
H       0.310560   0.155171   0.466239
H       0.579313   0.789364   0.367886
H       0.420687   0.210636   0.632114
H       0.735114   0.160862   0.564411
H       0.264886   0.839138   0.435589
H       0.841142   0.678921   0.395960
H       0.158858   0.321079   0.604040
H       0.704775   0.649736   0.414285
H       0.295225   0.350264   0.585715
H       0.719695   0.676825   0.585741
H       0.280305   0.323175   0.414259
H       0.842147   0.808299   0.622875
H       0.157853   0.191701   0.377125
H       0.909131   0.040565   0.586306
H       0.090869   0.959435   0.413694
H       0.813329   0.030924   0.623104
H       0.186671   0.969076   0.376896
H       0.235671   0.555603   0.395626
H       0.764329   0.444397   0.604374
H       0.360678   0.709558   0.414549
H       0.639322   0.290442   0.585451
H       0.547082   0.867749   0.588341
H       0.452918   0.132251   0.411659
H       0.592225   0.777421   0.623171
H       0.407775   0.222579   0.376829
H       0.244872   0.570226   0.479705
H       0.755128   0.429774   0.520295
H       0.330351   0.493981   0.475924
H       0.669649   0.506019   0.524076
H       0.350554   0.447464   0.334884
H       0.649446   0.552536   0.665116
H       0.401359   0.578319   0.563975
H       0.598641   0.421681   0.436025
H       0.989675   0.829464   0.564572
H       0.010325   0.170536   0.435428
H       0.636243   0.651000   0.315864
H       0.363757   0.349000   0.684136
H       0.665570   0.767051   0.279407
H       0.334430   0.232949   0.720593
H       0.906574   0.672742   0.479967
H       0.093426   0.327258   0.520033
H       0.980463   0.833857   0.475886
H       0.019537   0.166143   0.524114
H       0.334136   0.682448   0.318611
H       0.665864   0.317552   0.681389
H       0.380737   0.618096   0.280136
H       0.619263   0.381904   0.719864
H       0.889507   0.899211   0.336346
H       0.110493   0.100789   0.663654
H       0.521735   0.053523   0.338859
H       0.478265   0.946477   0.661141
H       0.402733   0.898831   0.338727
H       0.597267   0.101169   0.661273
H       0.722602   0.159289   0.396309
H       0.277398   0.840711   0.603691
H       0.764948   0.049312   0.415820
H       0.235052   0.950688   0.584180
H       0.665808   0.985717   0.317207
H       0.334192   0.014283   0.682793
H       0.515106   0.900474   0.279644
H       0.484894   0.099526   0.720356
H       0.806425   0.233379   0.480260
H       0.193575   0.766621   0.519740
H       0.640892   0.144925   0.475762
H       0.359108   0.855075   0.524238
C       0.755900   0.095000   0.554000
C       0.244100   0.905000   0.446000
C       0.804500   0.718000   0.416600
C       0.195500   0.282000   0.583400
C       0.789500   0.775500   0.588100
C       0.210500   0.224500   0.411900
C       0.812400   0.011800   0.588400
C       0.187600   0.988200   0.411600
C       0.331500   0.612000   0.416600
C       0.668500   0.388000   0.583400
C       0.576700   0.798900   0.588900
C       0.423300   0.201100   0.411100
C       0.330700   0.580900   0.471800
C       0.669300   0.419100   0.528200
C       0.385300   0.539100   0.347900
C       0.614700   0.460900   0.652100
C       0.459000   0.664200   0.553700
C       0.541000   0.335800   0.446300
C       0.892600   0.798100   0.554200
C       0.107400   0.201900   0.445800
C       0.663100   0.748000   0.313900
C       0.336900   0.252000   0.686100
C       0.888900   0.748300   0.471700
C       0.111100   0.251700   0.528300
C       0.401200   0.653000   0.315100
C       0.598800   0.347000   0.684900
C       0.809300   0.844000   0.348800
C       0.190700   0.156000   0.651200
C       0.505300   0.962400   0.347000
C       0.494700   0.037600   0.653000
C       0.700900   0.084100   0.417300
C       0.299100   0.915900   0.582700
C       0.566400   0.915600   0.314400
C       0.433600   0.084400   0.685600
C       0.723500   0.139900   0.472100
C       0.276500   0.860100   0.527900
$\endgroup$
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  • 1
    $\begingroup$ +1 Welcome to our forum! $\endgroup$
    – Camps
    Oct 22, 2023 at 22:42
  • $\begingroup$ 1/2) Could you add the full output file? I think you can check two things: First, you can check how the BFGS accuracy is changing with respect to the increasing number of iteration. If it is changing wildly/rapidly in an alternating manner, there is no reason to increase the nstep. You can increase it if you see some kind of systematic convergence with respect to increasing number of BFGS iteration. $\endgroup$ Oct 23, 2023 at 8:00
  • $\begingroup$ 2/2) Second, instead of starting the potential from atomic charge superposition, next time when you do the calculation, you can do with startingwfc='file' and startingpot='file'. Do not delete the temporary files produced by the previous calculation. This way your new calculation will choose the initial guess of the wavefunction and the potential from the output of the previous calculation. $\endgroup$ Oct 23, 2023 at 8:02
  • $\begingroup$ the scf calculation already converged twice once after 91 iterations and the second is after 70 but failed to converge for the third time. I do not know actually how to check for the bfgs accuracy could you tell me how? I'm kinda new to QE $\endgroup$ Oct 23, 2023 at 15:31
  • $\begingroup$ Could you please upload the output file? This is a very large system so the convergence issue can arise from many aspects. To check the bfgs accuracy, you can look for certain keyword in your output file such as: number of scf cycles, number of bfgs steps, Energy error, Gradient error, Cell gradient error, total stress etc and check how they changes. $\endgroup$ Oct 23, 2023 at 19:39

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