[QE-users] SCF convergence for a large system size

Vidushi Sharma vidushi.sharma at stonybrook.edu
Mon Jun 17 18:46:23 CEST 2019


Hi,

I am new to using Quantum Espresso and I have a question about the
convergence of a single point calculation ('scf') for a big system. The
system is not complicated at all -- just has one NaCl with 96 H_{2}O
molecules, but the box size itself has to be of the order of 15 Ang, and
this is not easy to converge. I have included my input file and the names
of the pseudopotentials I use from the set provided on the QE page -- any
suggestions to help the system converge are welcome! So far I have already
looked at ample of questions posted by people facing convergence issues but
nothing has improved the situation, and I have tested convergence on *smaller
sized* boxes and that seems to work fine with the given pseudopotentials
and other input parameters.

<nacl96h2o.in>
 &control
    calculation = 'scf',
    prefix = 'nacl_bh20',
    outdir = './tmp/'
    pseudo_dir = './pseudo/'
 /
 &system
    ibrav =  0,
    celldm(1) = 2.7161,
    nat =  290,
    ntyp = 4,
    ecutwfc = 30,
    ecutrho = 300,
    input_dft = 'pbe'
 /
 &electrons
    electron_maxstep = 500
    mixing_beta = 0.1
 /
CELL_PARAMETERS cubic
10.0  0.0  0.0
 0.0 10.0  0.0
 0.0  0.0 10.0

ATOMIC_SPECIES
 H  1.008   H.pbe-kjpaw_psl.1.0.0.UPF
 O  15.999  O.pbe-n-rrkjus_psl.1.0.0.UPF
 Na 22.990  Na.pbe-spn-kjpaw_psl.1.0.0.UPF
 Cl 35.453  Cl.pbe-n-kjpaw_psl.1.0.0.UPF

ATOMIC_POSITIONS (angstrom)
 Na      4.867210    6.569511    3.191487
 Cl      3.022620    6.024626    3.739746
 H       4.927055   10.441872   10.973286
 O       5.265258   11.309878   11.237590
 O       4.017527   10.622927   10.687648
 H      10.513380   12.871681    6.303561
 O      10.299966   13.812005    6.240642
 O       9.894495   12.512459    6.936896
 H       9.703393    1.257187    5.788580
 O       9.038896    1.890310    6.079435
 O      10.285630    1.775452    5.225542
 H      13.566921   11.356925   11.825488
 O      12.924065   12.026841   11.564094
 O      13.781250   10.904109   10.994968
 H      10.242246   12.399511    3.642226
 O      10.066306   12.118387    4.538761
 O       9.555536   13.037468    3.451166
 H       5.829184    8.701401    2.767993
 O       6.729539    9.014773    2.761105
 O       5.386785    9.232181    2.090447
 H      11.091427    3.643833   10.607679
 O      11.811736    4.275171   10.644902
 O      11.335723    2.981156   11.264805
 H       9.454174    9.724098   11.479173
 O       8.691027   10.116981   11.907536
 O      10.214669   10.182383   11.840996
 H       4.987285   14.324963    2.598627
 O       4.164732    0.116950    3.044210
 O       4.734860   13.960167    1.751422
 H      11.168902    1.973517   13.167202
 O      11.713195    2.466000   13.815669
 O      11.141319    1.075927   13.519426
 H       5.117969    2.634384    2.298544
 O       5.233954    1.711059    2.548705
 O       6.006517    2.987438    2.263779
 H       2.310572    7.428690   11.436984
 O       1.479980    6.953150   11.520516
 O       2.994438    6.771515   11.589829
 H      10.442356    9.367202    4.517214
 O      10.435523    9.843960    3.688311
 O       9.516179    9.363463    4.811819
 H       7.385970    1.426864   11.920237
 O       7.933397    1.724601   12.655179
 O       8.025128    1.093024   11.291179
 H       1.020593    2.001328   10.016276
 O       1.185432    2.127692   10.941944
 O       1.686152    1.378979    9.732610
 H      13.782330    3.290728    5.058812
 O      13.840035    2.871929    5.932143
 O      14.368339    2.769240    4.517663
 H      10.505698   10.102401    1.756034
 O      11.122516   10.281291    1.048208
 O      10.165230   10.961529    1.992476
 H       8.300607    5.454676   13.829578
 O       9.130585    5.611865   14.271766
 O       8.529094    5.384478   12.896466
 H       8.127639    5.739223    8.596007
 O       7.865767    6.662846    8.631549
 O       8.449893    5.573423    9.491189
 H       3.199780   10.559924    4.401587
 O       2.586694   10.215005    3.735467
 O       3.249385    9.885630    5.080991
 H       5.713466   11.322698    4.713134
 O       4.914592   11.026943    4.320960
 O       5.830766   12.191497    4.342987
 H       0.385969   12.163029    1.301139
 O       0.346916   13.114277    1.243542
 O      14.188198   11.950198    2.049644
 H      13.011027    2.643821    0.842728
 O      12.754584    2.331435    1.708804
 O      13.640876    1.988495    0.519065
 H       6.931294    9.346607   13.782798
 O       6.354101    8.621786   13.489437
 O       7.440681    8.973331    0.124115
 H      12.433086    8.971692    6.683760
 O      12.150275    8.306837    7.313441
 O      11.645473    9.141284    6.152326
 H      13.055595   12.091450    7.048727
 O      13.466587   12.922496    7.308617
 O      12.197462   12.343484    6.653975
 H       0.116658    4.687688    1.679807
 O      13.818174    4.056432    1.403838
 O       0.389399    4.404455    2.551999
 H       2.810947   10.512739    1.219633
 O       2.029966   11.078473    1.299794
 O       2.625997    9.935129    0.494591
 H      13.692304    1.772216    7.294778
 O      12.740134    1.931271    7.375310
 O      14.093933    2.452758    7.849110
 H       3.756586    1.852312    6.287004
 O       4.661857    1.858215    5.988074
 O       3.296722    1.396284    5.591416
 H       5.013538    3.351031   11.806268
 O       5.667354    2.646508   11.788579
 O       4.536437    3.271915   10.985177
 H       6.120018    4.506023    7.273240
 O       5.428645    4.458205    7.944853
 O       6.908423    4.868345    7.731643
 H      10.564147    5.914150    0.851846
 O      11.297190    6.391602    0.500389
 O      10.761905    5.757775    1.769700
 H       4.209058   12.791475    0.280627
 O       3.605348   12.787683   13.898476
 O       3.983161   11.999365    0.761822
 H       6.781484   12.022692   13.963930
 O       6.727285   11.066180   13.867317
 O       5.869490   12.310230   14.071349
 H       6.310932   13.150393   11.440921
 O       6.431318   14.095211   11.464492
 O       6.400192   12.859149   12.360045
 H       1.980944   12.252419    6.107114
 O       2.202650   11.602418    5.442023
 O       1.077861   12.048021    6.346127
 H       4.690337    6.089800   11.822453
 O       5.360804    6.388037   11.213363
 O       4.891455    5.153594   11.979456
 H      11.083520    6.389237    3.367335
 O      11.996878    6.127900    3.534797
 O      11.003236    7.259621    3.742246
 H      13.274863   11.046655    3.193857
 O       12.579058   11.676604    3.333482
 O      13.260408   10.466810    3.952280
 H       8.872945    5.047963   11.111122
 O       9.230930    5.937410   10.954740
 O       9.542287    4.442152   10.794840
 H       0.451212    7.710015    1.416153
 O       0.683966    6.830906    1.655804
 O       1.143971    7.978834    0.816618
 H       8.444275    2.671614   14.296021
 O       9.288997    2.441563   13.910468
 O       8.280653    3.569879   14.014529
 H       6.459516    6.860116    5.230569
 O       6.123324    6.315491    5.953433
 O       7.292196    6.445562    4.990060
 H      14.253197    0.322980    0.589961
 O       0.395995    0.482805   14.172782
 O      13.396323    0.015569    0.261483
 H       7.925063   14.078269    3.552169
 O       7.269108    0.308592    3.153432
 O       8.154069    0.131098    4.376061
 H       8.959624   13.215240   10.765021
 O       8.047759   13.057036   10.980113
 O       9.021536   13.063602    9.819968
 H       3.066014    0.653318    9.085639
 O       3.506412    1.320280    8.541030
 O       3.448989   14.215855    8.803568
 H       8.445248    8.287719    1.334805
 O       9.105063    7.753954    0.856524
 O       8.917019    9.097561    1.566098
 H      11.429143    2.335868    3.858027
 O      11.675925    1.442362    3.574269
 O      12.204733    2.644049    4.338440
 H      13.354510    5.966928    9.874683
 O      13.789329    5.820085   10.731269
 O      13.884401    5.448158    9.250328
 H      13.748491   10.353042    9.211821
 O      13.324978   10.857040    8.523345
 O      14.101161    9.588461    8.766131
 H       3.569789    1.883910   13.653641
 O       4.064447    2.282077   12.941204
 O       4.090613    2.054684    0.049521
 H      11.140485    1.957873    8.592517
 O      10.443164    2.320496    8.038523
 O      11.142660    2.524443    9.369447
 H       2.465981   11.089071    9.939744
 O       1.618936   10.936876    9.509961
 O       2.898414   11.751751    9.376324
 H       2.335577    8.432626   14.074842
 O       3.095595    7.882333   14.228272
 O       2.286556    8.545374   13.118974
 H       1.276355    0.663073   12.705923
 O       2.068326    1.134119   12.953695
 O       1.600297   14.199693   12.366240
 H      11.438586   13.195259   11.730789
 O      11.939166   13.662581   11.047674
 O      10.536523   13.153140   11.379754
 H       7.543757    9.464864    4.924522
 O       6.948121   10.200637    4.798178
 O       6.985251    8.693839    5.014859
 H       0.089816    5.866065   12.280984
 O      13.963163    6.340195   12.949559
 O       0.470776    5.096317   12.734193
 H       0.784890    1.259950    3.393559
 O       0.350970    0.924577    2.612637
 O       1.351487    1.961401    3.062714
 H       1.355084    3.814694   13.615672
 O       2.227064    3.454467   13.747785
 O       1.063317    4.074885    0.124062
 H       3.626148   12.687697    8.037170
 O       3.026220   12.319487    7.379165
 O       4.487389   12.347781    7.775430
 H       7.873957    2.652922    2.595999
 O       8.034399    3.541204    2.934007
 O       8.363971    2.618829    1.765769
 H       6.230319    7.883032   10.181265
 O       5.735556    8.612376   10.530609
 O       6.683240    8.241272    9.425185
 H       2.407346    4.210697    7.030739
 O       2.848246    3.491015    6.558082
 O       2.295683    4.904306    6.367323
 H       3.671794    8.139713    6.036689
 O       4.271273    7.697943    6.659497
 O       3.584450    7.521915    5.321453
 H       8.829549   13.412907    0.585991
 O       8.592220   14.102131    1.206679
 O       7.998748   12.980611    0.383450
 H       2.443830   12.538891   12.560835
 O       1.575220   12.173028   12.648057
 O       2.678483   12.409693   11.646485
 H       0.534107   13.873962    8.287769
 O       0.022520    0.274723    8.024468
 O       1.442664   14.139814    8.191882
 H       0.364690    9.744231    6.043366
 O      13.797970    9.587365    6.128301
 O       0.547946    9.542747    5.124702
 H       9.565251    3.827275    7.247780
 O      10.415887    4.268975    7.389913
 O       8.938873    4.384416    7.698194
 H      13.540610    6.144147    4.940110
 O      13.786015    5.241364    5.152882
 O      14.177865    6.664019    5.439124
 H       6.483650    6.233767    1.404497
 O       7.051697    6.982300    1.600908
 O       7.059132    5.596429    0.995926
 H       3.592029    7.510042    9.040455
 O       4.389035    7.569923    9.560856
 O       2.901807    7.889327    9.590652
 H       1.140225    7.185179    6.958092
 O       0.898785    8.105436    6.823741
 O       2.076957    7.150791    6.801894
 H      12.776424    7.353301   13.990676
 O      12.813274    8.268671   13.760081
 O      13.385771    7.254497    0.355907
 H      12.185343   14.216578    2.763006
 O      11.973102   14.101034    1.836881
 O      11.530400   13.718416    3.242987
 H      12.590676    0.081501    9.871654
 O      12.183736    0.685923    9.248364
 O      13.514462    0.340792    9.885274
 H      10.529125    7.165842   10.860387
 O      10.780397    7.181242    9.935563
 O      10.292923    8.067736   11.059361
 H       9.542964    9.265963    8.778407
 O       9.655647    9.599469    9.660658
 O     10.309278    8.716008    8.623187
 H      12.602271   10.172732   14.171242
 O      12.548670   10.660947   13.362317
 O      13.376187   10.533582    0.248283
 H       2.382078    3.112711    2.361329
 O       2.319961    3.996877    2.712884
 O       3.309781    2.893447    2.471644
 H       0.187558    4.340477    8.250686
 O       0.976324    4.352700    7.700495
 O       0.325105    3.592681    8.832424
 H      11.659327   13.588808    0.140072
 O      10.701608   13.548170    0.199567
 O      11.868008   13.242048   13.640385
 H       8.818772   11.915113    8.170347
 O       9.160246   11.026199    8.156220
 O       7.876547   11.825312    7.972383
 H       6.953861    2.263551    5.723934
 O       7.336427    2.562735    4.895815
 O       6.885956    3.060728    6.255275
 H      11.442463    7.477512    8.438407
 O      12.075532    7.198556    9.069157
 O      11.189573    6.672282    7.958267
 H       5.984810   11.452681    7.625950
 O       5.728554   10.574700    7.945014
 O       5.752343   11.454954    6.692076
 H       8.931983    5.294554    4.433915
 O       9.734654    5.707683    4.109957
 O       9.238577    4.639954    5.081587
 H      11.828368    5.378873    6.956136
 O      12.465835    4.970816    7.538112
 O      12.336737    5.609106    6.175822
 H       7.301143    8.610338    7.491834
 O       8.019254    8.945782    8.007879
 O       7.554967    8.781518    6.582434
 H       2.741984    0.009479    4.583960
 O       2.325315   13.652372    5.050994
 O       1.999228    0.437728    4.150440
 H       4.078126    4.480106    9.256640
 O       3.532034    4.273291    8.466345
 O       3.819014    5.370796    9.487585
 H       4.777059    7.388148   14.094417
 O       4.798602    6.900684   13.257178
 O       5.480806    6.997436    0.231650
 H       1.009654    8.870862    3.650558
 O       0.610210    8.418493    2.883665
 O       1.631243    8.220421    4.008205


Thank you
Regards,

Vidushi Sharma
PhD student, Computational Condensed Matter Physics,
Stony Brook University,
NY-11780
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