<div dir="ltr"><div>Hi,</div><div><br></div><div>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 webpage -- 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 <b>smaller sized</b> boxes and that seems to work fine with the given pseudopotentials and other input parameters. I am currently using input_dft= 'pbe' (which is consistent with the pseudopotentials) but I eventually want to work with the available hybrid XC.<br></div><div><br></div><div><<a href="http://nacl96h2o.in" target="_blank">nacl96h2o.in</a>></div><div> &control<br>    calculation = 'scf',<br>    prefix = 'nacl_bh20',<br>    outdir = './tmp/'<br>    pseudo_dir = './pseudo/'<br> /<br> &system<br>    ibrav =  0, <br>    celldm(1) = 2.7161, <br>    nat =  290, <br>    ntyp = 4,<br>    ecutwfc = 30,<br>    ecutrho = 300,<br>    input_dft = 'pbe'<br> /<br> &electrons<br>    electron_maxstep = 500<br>    mixing_beta = 0.1<br> /<br>CELL_PARAMETERS cubic<br>10.0  0.0  0.0<br> 0.0 10.0  0.0<br> 0.0  0.0 10.0<br><br>ATOMIC_SPECIES<br> H  1.008   H.pbe-kjpaw_psl.1.0.0.UPF   <br> O  15.999  O.pbe-n-rrkjus_psl.1.0.0.UPF <br> Na 22.990  Na.pbe-spn-kjpaw_psl.1.0.0.UPF<br> Cl 35.453  Cl.pbe-n-kjpaw_psl.1.0.0.UPF <br><br>ATOMIC_POSITIONS (angstrom)<br> Na      4.867210    6.569511    3.191487<br> Cl      3.022620    6.024626    3.739746<br> H       4.927055   10.441872   10.973286<br> O       5.265258   11.309878   11.237590<br> O       4.017527   10.622927   10.687648<br> H      10.513380   12.871681    6.303561<br> O      10.299966   13.812005    6.240642<br> O       9.894495   12.512459    6.936896<br> H       9.703393    1.257187    5.788580<br> O       9.038896    1.890310    6.079435<br> O      10.285630    1.775452    5.225542<br> H      13.566921   11.356925   11.825488<br> O      12.924065   12.026841   11.564094<br> O      13.781250   10.904109   10.994968<br> H      10.242246   12.399511    3.642226<br> O      10.066306   12.118387    4.538761<br> O       9.555536   13.037468    3.451166<br> H       5.829184    8.701401    2.767993<br> O       6.729539    9.014773    2.761105<br> O       5.386785    9.232181    2.090447<br> H      11.091427    3.643833   10.607679<br> O      11.811736    4.275171   10.644902<br> O      11.335723    2.981156   11.264805<br> H       9.454174    9.724098   11.479173<br> O       8.691027   10.116981   11.907536<br> O      10.214669   10.182383   11.840996<br> H       4.987285   14.324963    2.598627<br> O       4.164732    0.116950    3.044210<br> O       4.734860   13.960167    1.751422<br> H      11.168902    1.973517   13.167202<br> O      11.713195    2.466000   13.815669<br> O      11.141319    1.075927   13.519426<br> H       5.117969    2.634384    2.298544<br> O       5.233954    1.711059    2.548705<br> O       6.006517    2.987438    2.263779<br> H       2.310572    7.428690   11.436984<br> O       1.479980    6.953150   11.520516<br> O       2.994438    6.771515   11.589829<br> H      10.442356    9.367202    4.517214<br> O      10.435523    9.843960    3.688311<br> O       9.516179    9.363463    4.811819<br> H       7.385970    1.426864   11.920237<br> O       7.933397    1.724601   12.655179<br> O       8.025128    1.093024   11.291179<br> H       1.020593    2.001328   10.016276<br> O       1.185432    2.127692   10.941944<br> O       1.686152    1.378979    9.732610<br> H      13.782330    3.290728    5.058812<br> O      13.840035    2.871929    5.932143<br> O      14.368339    2.769240    4.517663<br> H      10.505698   10.102401    1.756034<br> O      11.122516   10.281291    1.048208<br> O      10.165230   10.961529    1.992476<br> H       8.300607    5.454676   13.829578<br> O       9.130585    5.611865   14.271766<br> O       8.529094    5.384478   12.896466<br> H       8.127639    5.739223    8.596007<br> O       7.865767    6.662846    8.631549<br> O       8.449893    5.573423    9.491189<br> H       3.199780   10.559924    4.401587<br> O       2.586694   10.215005    3.735467<br> O       3.249385    9.885630    5.080991<br> H       5.713466   11.322698    4.713134<br> O       4.914592   11.026943    4.320960<br> O       5.830766   12.191497    4.342987<br> H       0.385969   12.163029    1.301139<br> O       0.346916   13.114277    1.243542<br> O      14.188198   11.950198    2.049644<br> H      13.011027    2.643821    0.842728<br> O      12.754584    2.331435    1.708804<br> O      13.640876    1.988495    0.519065<br> H       6.931294    9.346607   13.782798<br> O       6.354101    8.621786   13.489437<br> O       7.440681    8.973331    0.124115<br> H      12.433086    8.971692    6.683760<br> O      12.150275    8.306837    7.313441<br> O      11.645473    9.141284    6.152326<br> H      13.055595   12.091450    7.048727<br> O      13.466587   12.922496    7.308617<br> O      12.197462   12.343484    6.653975<br> H       0.116658    4.687688    1.679807<br> O      13.818174    4.056432    1.403838<br> O       0.389399    4.404455    2.551999<br> H       2.810947   10.512739    1.219633<br> O       2.029966   11.078473    1.299794<br> O       2.625997    9.935129    0.494591<br> H      13.692304    1.772216    7.294778<br> O      12.740134    1.931271    7.375310<br> O      14.093933    2.452758    7.849110<br> H       3.756586    1.852312    6.287004<br> O       4.661857    1.858215    5.988074<br> O       3.296722    1.396284    5.591416<br> H       5.013538    3.351031   11.806268<br> O       5.667354    2.646508   11.788579<br> O       4.536437    3.271915   10.985177<br> H       6.120018    4.506023    7.273240<br> O       5.428645    4.458205    7.944853<br> O       6.908423    4.868345    7.731643<br> H      10.564147    5.914150    0.851846<br> O      11.297190    6.391602    0.500389<br> O      10.761905    5.757775    1.769700<br> H       4.209058   12.791475    0.280627<br> O       3.605348   12.787683   13.898476<br> O       3.983161   11.999365    0.761822<br> H       6.781484   12.022692   13.963930<br> O       6.727285   11.066180   13.867317<br> O       5.869490   12.310230   14.071349<br> H       6.310932   13.150393   11.440921<br> O       6.431318   14.095211   11.464492<br> O       6.400192   12.859149   12.360045<br> H       1.980944   12.252419    6.107114<br> O       2.202650   11.602418    5.442023<br> O       1.077861   12.048021    6.346127<br> H       4.690337    6.089800   11.822453<br> O       5.360804    6.388037   11.213363<br> O       4.891455    5.153594   11.979456<br> H      11.083520    6.389237    3.367335<br> O      11.996878    6.127900    3.534797<br> O      11.003236    7.259621    3.742246<br> H      13.274863   11.046655    3.193857<br> O       12.579058   11.676604    3.333482<br> O      13.260408   10.466810    3.952280<br> H       8.872945    5.047963   11.111122<br> O       9.230930    5.937410   10.954740<br> O       9.542287    4.442152   10.794840<br> H       0.451212    7.710015    1.416153<br> O       0.683966    6.830906    1.655804<br> O       1.143971    7.978834    0.816618<br> H       8.444275    2.671614   14.296021<br> O       9.288997    2.441563   13.910468<br> O       8.280653    3.569879   14.014529<br> H       6.459516    6.860116    5.230569<br> O       6.123324    6.315491    5.953433<br> O       7.292196    6.445562    4.990060<br> H      14.253197    0.322980    0.589961<br> O       0.395995    0.482805   14.172782<br> O      13.396323    0.015569    0.261483<br> H       7.925063   14.078269    3.552169<br> O       7.269108    0.308592    3.153432<br> O       8.154069    0.131098    4.376061<br> H       8.959624   13.215240   10.765021<br> O       8.047759   13.057036   10.980113<br> O       9.021536   13.063602    9.819968<br> H       3.066014    0.653318    9.085639<br> O       3.506412    1.320280    8.541030<br> O       3.448989   14.215855    8.803568<br> H       8.445248    8.287719    1.334805<br> O       9.105063    7.753954    0.856524<br> O       8.917019    9.097561    1.566098<br> H      11.429143    2.335868    3.858027<br> O      11.675925    1.442362    3.574269<br> O      12.204733    2.644049    4.338440<br> H      13.354510    5.966928    9.874683<br> O      13.789329    5.820085   10.731269<br> O      13.884401    5.448158    9.250328<br> H      13.748491   10.353042    9.211821<br> O      13.324978   10.857040    8.523345<br> O      14.101161    9.588461    8.766131<br> H       3.569789    1.883910   13.653641<br> O       4.064447    2.282077   12.941204<br> O       4.090613    2.054684    0.049521<br> H      11.140485    1.957873    8.592517<br> O      10.443164    2.320496    8.038523<br> O      11.142660    2.524443    9.369447<br> H       2.465981   11.089071    9.939744<br> O       1.618936   10.936876    9.509961<br> O       2.898414   11.751751    9.376324<br> H       2.335577    8.432626   14.074842<br> O       3.095595    7.882333   14.228272<br> O       2.286556    8.545374   13.118974<br> H       1.276355    0.663073   12.705923<br> O       2.068326    1.134119   12.953695<br> O       1.600297   14.199693   12.366240<br> H      11.438586   13.195259   11.730789<br> O      11.939166   13.662581   11.047674<br> O      10.536523   13.153140   11.379754<br> H       7.543757    9.464864    4.924522<br> O       6.948121   10.200637    4.798178<br> O       6.985251    8.693839    5.014859<br> H       0.089816    5.866065   12.280984<br> O      13.963163    6.340195   12.949559<br> O       0.470776    5.096317   12.734193<br> H       0.784890    1.259950    3.393559<br> O       0.350970    0.924577    2.612637<br> O       1.351487    1.961401    3.062714<br> H       1.355084    3.814694   13.615672<br> O       2.227064    3.454467   13.747785<br> O       1.063317    4.074885    0.124062<br> H       3.626148   12.687697    8.037170<br> O       3.026220   12.319487    7.379165<br> O       4.487389   12.347781    7.775430<br> H       7.873957    2.652922    2.595999<br> O       8.034399    3.541204    2.934007<br> O       8.363971    2.618829    1.765769<br> H       6.230319    7.883032   10.181265<br> O       5.735556    8.612376   10.530609<br> O       6.683240    8.241272    9.425185<br> H       2.407346    4.210697    7.030739<br> O       2.848246    3.491015    6.558082<br> O       2.295683    4.904306    6.367323<br> H       3.671794    8.139713    6.036689<br> O       4.271273    7.697943    6.659497<br> O       3.584450    7.521915    5.321453<br> H       8.829549   13.412907    0.585991<br> O       8.592220   14.102131    1.206679<br> O       7.998748   12.980611    0.383450<br> H       2.443830   12.538891   12.560835<br> O       1.575220   12.173028   12.648057<br> O       2.678483   12.409693   11.646485<br> H       0.534107   13.873962    8.287769<br> O       0.022520    0.274723    8.024468<br> O       1.442664   14.139814    8.191882<br> H       0.364690    9.744231    6.043366<br> O      13.797970    9.587365    6.128301<br> O       0.547946    9.542747    5.124702<br> H       9.565251    3.827275    7.247780<br> O      10.415887    4.268975    7.389913<br> O       8.938873    4.384416    7.698194<br> H      13.540610    6.144147    4.940110<br> O      13.786015    5.241364    5.152882<br> O      14.177865    6.664019    5.439124<br> H       6.483650    6.233767    1.404497<br> O       7.051697    6.982300    1.600908<br> O       7.059132    5.596429    0.995926<br> H       3.592029    7.510042    9.040455<br> O       4.389035    7.569923    9.560856<br> O       2.901807    7.889327    9.590652<br> H       1.140225    7.185179    6.958092<br> O       0.898785    8.105436    6.823741<br> O       2.076957    7.150791    6.801894<br> H      12.776424    7.353301   13.990676<br> O      12.813274    8.268671   13.760081<br> O      13.385771    7.254497    0.355907<br> H      12.185343   14.216578    2.763006<br> O      11.973102   14.101034    1.836881<br> O      11.530400   13.718416    3.242987<br> H      12.590676    0.081501    9.871654<br> O      12.183736    0.685923    9.248364<br> O      13.514462    0.340792    9.885274<br> H      10.529125    7.165842   10.860387<br> O      10.780397    7.181242    9.935563<br> O      10.292923    8.067736   11.059361<br> H       9.542964    9.265963    8.778407<br> O       9.655647    9.599469    9.660658<br> O     10.309278    8.716008    8.623187<br> H      12.602271   10.172732   14.171242<br> O      12.548670   10.660947   13.362317<br> O      13.376187   10.533582    0.248283<br> H       2.382078    3.112711    2.361329<br> O       2.319961    3.996877    2.712884<br> O       3.309781    2.893447    2.471644<br> H       0.187558    4.340477    8.250686<br> O       0.976324    4.352700    7.700495<br> O       0.325105    3.592681    8.832424<br> H      11.659327   13.588808    0.140072<br> O      10.701608   13.548170    0.199567<br> O      11.868008   13.242048   13.640385<br> H       8.818772   11.915113    8.170347<br> O       9.160246   11.026199    8.156220<br> O       7.876547   11.825312    7.972383<br> H       6.953861    2.263551    5.723934<br> O       7.336427    2.562735    4.895815<br> O       6.885956    3.060728    6.255275<br> H      11.442463    7.477512    8.438407<br> O      12.075532    7.198556    9.069157<br> O      11.189573    6.672282    7.958267<br> H       5.984810   11.452681    7.625950<br> O       5.728554   10.574700    7.945014<br> O       5.752343   11.454954    6.692076<br> H       8.931983    5.294554    4.433915<br> O       9.734654    5.707683    4.109957<br> O       9.238577    4.639954    5.081587<br> H      11.828368    5.378873    6.956136<br> O      12.465835    4.970816    7.538112<br> O      12.336737    5.609106    6.175822<br> H       7.301143    8.610338    7.491834<br> O       8.019254    8.945782    8.007879<br> O       7.554967    8.781518    6.582434<br> H       2.741984    0.009479    4.583960<br> O       2.325315   13.652372    5.050994<br> O       1.999228    0.437728    4.150440<br> H       4.078126    4.480106    9.256640<br> O       3.532034    4.273291    8.466345<br> O       3.819014    5.370796    9.487585<br> H       4.777059    7.388148   14.094417<br> O       4.798602    6.900684   13.257178<br> O       5.480806    6.997436    0.231650<br> H       1.009654    8.870862    3.650558<br> O       0.610210    8.418493    2.883665<br> O       1.631243    8.220421    4.008205</div><div><br></div><div><br></div><div>Thank you</div><div>Regards,</div><div><br></div><div>Vidushi Sharma</div><div>PhD student, Computational Condensed Matter Physics,</div><div>Stony Brook University,</div><div>NY-11780</div></div>